Product Reviewed: SAE 5W-30 Signature Series 100% Synthetic Motor Oil (ASL)
Current Rating: 4.97 out of 5 stars
Votes & Reviews: 1010 vote(s) and 1476 user reviews.
Reviewed by Todd: 
Good value for 12 month protection.
Reviewed by Ironrider1550:
I use this in my chevy truck. I love the extended drain as it helps save me money and time. The oil still feels great when drained.
Reviewed by HJH:
I have used this product in my 2 vehicles since their first oil change. My 2007 Tahoe has 191,000 miles on it and I expect it will perform for many years to come. Although the oil and filter are rated for 25,000 miles or once a year, I still change oil and filter every 6 months; very reasonsonable amount to spend for a bit of extra insurance. I assume my engine is finally broken in since it regularly achieves 20 mpg on the highway.
Reviewed by mm:
keeps my engine running great
Reviewed by Tu D Truong:
I really like so much AMSOIL suythetic oil products
Reviewed by Shawn of Indy:
I've been a customer for ten years now and have always used the Signature 5W-30 in my vehicles. I still own the same vehicles and change my oil once a year. I don't worry much about tracking the mileage but it usually ends up being 16,000 +\-. I'm confident their lubricant is protecting my engines at this mileage and only changing it annually has actually saved me money.
Reviewed by Skylukewalker:
I don't really have time to change my oil every 2 to 3 months, so I use amsoil, it is the best bet to keep my car running even if I only change the oil once a year. And I actually save money using Amsoil's best oil once a year than to use a cheap oil every few months. ...a no brainer if you ask me.
Reviewed by Viking Bob:
I have been using Amsoil since the early 1980s all my vehicles, recreational toys, and tools. I have never had any issues. The cheapening of the word "synthetic" by Castol winning their court case has made it less clear what one is actually buying when the oil is labeled synthetic. Amsoil pioneered the synthetic oil industry and can still be trusted not to hide behind using the word "synthetic" as only a marketing ploy. I also use the 0w20 oil as specified in my newer Mazda 6. I do all my own maintenance and will continue to use only Amsoil.
Reviewed by The Flash (Gordon):
I have been using Amsoil products for 18 years. I started with my 1998 Chevy K1500 Suburban which I bought new and started using Amsoil oil when it had 38,000 kms. It now has 423,000 kms and is running as strong as the day I bought it.
I firmly believe that Amsoil and regular maintenance, which I do mostly myself, are the reasons why this truck has lasted so long and has run so well for all these years.
Reviewed by SilverEvoX:
I use it everytime I do my oil change. Car runs smoother and better.
Reviewed by Retired
Sergeant:
I really love this stuff. I used to worry about my lubrication needs. Always thinking, my brand new truck isn't getting enough protection. Now, I don't worry about a thing until 10K or 15K depending on how I use my truck. Going from the Midwest to the west on vacation always concerned me because of the difference in Temperature and terrain. Now, I know my truck is protected.
Reviewed by Revrat:
I use this product in all my vehicles, and have converted many friends to its use. Engines run quieter and seem to run smoother after converting to Amsoil.
Reviewed by JKman:
Put Amsoil Signature Series 5W-30 in our 2016 Wranglers and noticed both an increase in mileage and an end to the occasion start-up tick which happened on occasion. Never using any other oil than Amsoil in the future.
Reviewed by D:
So far so good
Reviewed by Wayne:
It is expensive, but worth every penny. Instead of replacing every 3000 miles, it is once a year!
Reviewed by Big D:
Interval of change time is great. Better gas mileage in my pickup. Works great great product.
Reviewed by KP:
Great oil.
Reviewed by Mcm:
When I first bought my vehicle used, the oil changes looked super sludgy, and the gas mileage was pretty poor. After 1 oil change with amsoil full synthetic with the ea filter, it is clean clean clean and I have 1mpg better fuel mileage after a little over 5000 miles. With any other oil, it would be black and gritty looking. I also like the extended drain intervals provided with this oils capability, so I only have to change my oil once per year.
Reviewed by Mike:
Great product. Prolongs engine life.
Reviewed by Bigtrain:
I have 170,000+ miles, after the 36,000 mile factory warranty ran out it has been Amsiol ever
since.
I use the 25,000 mile signature series with never a problem. I have to change the filter half way thru because I can only find a 15,000 mile filter, I have to add between 1/2 and 3/4 quart at this time. I always change oil around 24,000 miles unless I have been pulling my 7,000lbs for over 1,000 total between changes then for piece of mind I change at 20,000 miles. I drive a 2008 Toyota FJ Cruiser and take it off-road
Reviewed by EB:
I've used AMSoil in all my vehicles including my Harley's since I purchased them, used or new and I will never go back to off the shelf products again. The cost difference is insignificant so it only makes sense to use the best.
Reviewed by pilgrim:
Best oil on the market.
Reviewed by Scott:
Had some other people talk about benefits of Amsoil. Started using it in my '98 Ford Ranger with 108,000 miles on it. Sent in samples and at 185,000 miles truck was cleaner engine wise then it was at the start. At about 265,000 miles sucked a valve so had son put new heads on it. When tore into engine was no sludge or carbon on top of block and the timing chain looked like brand new. Son traded the truck in on newer one at 365,000 miles and still was running good. I use Amsoil in all my vehicles and yard equipment.
Reviewed by JP:
I added Amsoil 5w30 Signature to my 08 350Z HR. I noticed an increase in power immediately. I'm running against cars with much more power, and outperforming them, thanks to what feels like quicker acceleration through the rpm range. I recommend this product for all engines, as no other oil comes close.
Reviewed by Weekend mechanic:
I use this my children use it in my friends use this. We enjoy the fuel savings less engine friction and longer service intervals it really saves a lot of money.
Reviewed by Joe:
I use this oil on all my small engines. My compressor used to trip the circuit breaker regularly until I switched to this synthetic blend. Hasn't tripped a breaker since even in the winter
Reviewed by racerbug:
I put Amsoil in ALL of my toys.
Reviewed by Jon:
Last time we had to order amsoil we received free shipping. That just added to the great deal we already get from them. We've been using amsoil products in or vehicles for 2 years now and nothing else compares.
Reviewed by Tim:
Longevity, reliability and ultimate protection
Reviewed by Biner:
Use this in my wifes Ford Explorer 4x4. It's got over a 100,000 on it and never had a problem and it run's like a top.
Reviewed by Steve:
I have been using this oil for 10 years on my 2006 Corolla, change the oil once a year, now have 168000 miles and still going strong
Reviewed by Chief:
I use 5w30 and 5w20 in all of my cars
Reviewed by Johhnystock:
I trust this oil. Running strong since one year. I use Zrod since cammed because of extra zinc but woulnd mind running Signatures series anyway.
Reviewed by Brian:
Great product,great price
Reviewed by Schlogg:
I've been using AMSOIL products for 3 years now, started with engine oil and have also explored brake fluid, gas additive, grease, tranny fluid and gear oil. I began with the XL line of products then moved to the signature series and know that is all that I use. I would recommend AMSOIL products to anyone.
Reviewed by Johnnystock:
I trust this oil. Running strong since one year. I use Zrod since cammed because of extra zinc but woulnd mind running Signatures series anyway.
Reviewed by Bud:
Best oil and value imho.
Reviewed by Chuck:
First and best synthetic moter oil. I keep my vehicles past 90,000 miles so I need a oil that will make them last.
Reviewed by Bob:
I have used this oil for years. The yearly or mileage intervals are great and saves money plus I get the best protection for my truck. I study oil test and Amsoil is the highest rated product.
Reviewed by JimmyJom:
I was using Mobil 1 Extended then I tried this. Man the truck runs smoother than ever, almost like new. I will never go back, all Amsoil from here on out!
Reviewed by Grizzle:
After I bought this car, I put in its first fill of Amsoil SS at 3,000 miles to get rid of the "dinosaur juice". Now after 230,000 miles, it will still get nothing but SS for its NEXT 230,000 miles. It runs PERFECTLY!
Reviewed by Jigger:
Have used AMSOIL sysnthetics for years. Have had new Tahoes and Buick Enclaves into shops and entire fluids changed to AMSOIL.
Reviewed by MPM:
I love your company. The best auto products on the market hands down and you always deliver without a glitch. Order is always accurate and the packaging is perfect. Thank you for the great service!!!!!
Reviewed by Nick Mac:
Use it in my Lexus with 290k on the clock. Smooth. Nice viscosity. Now use it in all my cars- always will.
Reviewed by Tinkerwatch:
I use this product in all three of my Toyotas.
It's a great motor oil! My engine seems quieter and smoother, I have not used it long enough yet to tell if my mileage has improved or not. I plan to continue using it from now on.
Reviewed by Jr:
I use the product for my oil changes, I've used many different oils but no one comes close to this. Loyal customer to this oil
Reviewed by none:
I have read all the material on oils . I use amsoil in both my cars, truck and both harley davidson motorcycles
Reviewed by Red:
Soon as I changed the oil I felt a difference in throttle response and shifting felt great little better mpg aswell
Reviewed by Luke:
It run a lot smoother than the P**$oil full synthetic I used during my last oil change and is definitely better than the dino juice it had in it when I bought it
Reviewed by Steve 1954 Chev:
I have been using this oil for years in myc1997 Honda. 235,000 miles later it runs like a gem! Nothing but the best for my cars and truck. Quality lubricant.
Reviewed by Tacoma Bob:
Used in all my P/U and SUV for past ten Years
Reviewed by Keyzbum:
This product lasts just like it says , a great product
Reviewed by beast:
I been using Amsoil Signature Series oil more than 10 years and long story short-i LOVE IT!!! If you care about your ride this is oil for you. HIGHLY RECOMMENDED!
Reviewed by Gump:
I have run Amsoil exclusively in everything I have that runs or moves. I'm convinced it has greatly extended the life of all the vehicles I own including my drag car. 8 seasons without a freshen up, and still going strong. Keeps internals spotless clean too. 40 below or 120 above, it's the best there is.
Reviewed by Freeman:
Shipping is expensive when I buy in bulk.
Reviewed by ulcivy:
I am using it for all my cars and trucks and I am saving a lot of time and money. Not to mention that my cars run good in all seasons.
Reviewed by JR:
I began using Amsoil products over a year ago. So far I have converted all my vehicles to Amsoil. Since changing to Amsoil, I noticed that the engines run much quieter and my gas mileage increased an average of 5 mpg. I like the extended drain intervals and the protection I get. I have two high mileage vehicles and I noticed that the oil is cleaner when I check the dipstick and it's not as dark as it was when using regular oil. I highly recommend this oil.
Reviewed by tonyturbo:
After 6000 miles oil is still clean
Reviewed by Big johnson:
This oil stands up excellent in my vehicle, the level never drops and even the colour of it doesnt change much between oil changes, never black when it comes out! Fantastic oil!
Reviewed by HD:
Use it in my 09 chevy z71 4x4 since new
Use in my wife's car.
Reviewed by d:
great product
Reviewed by Mtnbiker:
I've been using this oil for 3 years now. My 2007 F150 has 135000 on it now. I like only having to change my oil once a year.
Reviewed by Gene:
I have been using Signature Series 10W-30 Synthetic Motor Oil in my vehicles since 1998. I still use it in my 1997 Dodge Dakota pickup, which now has just under 120,000 miles on it and it still doesn't use any oil, even though I only change oil every 15,000 miles, and only change the filter every 7,500 miles. I was using this same oil in my 1998 Dodge Intrepid sedan until we were involved in an accident with it in 2012, at which time the vehicle was declared a total loss (with just over 214,000 miles on it, and it still wasn't using any oil, even though I only changed oil on it every 20,000 miles, and only changed the filter every 10,000 miles. Up until the time the car was declared a total loss, the engine had never been worked on for anything other than changing the spark plugs every 100,000 miles. We would still be driving it if it hadn't been for the accident that made it a total loss.
Reviewed by Rob:
Been using this oil for 12 years.
Reviewed by Big L:
I only use Amsoil in all my vehicles. Amsoil extends my oil change intervals and improves my engine performance. I'm well pleased with how this oil performs against conventional oil that I used in the past.
Reviewed by Chuck:
I put 100 miles a day on my daily driver. I purchased it with 40,000 miles on the odometer now it has 84,000 miles on it. 4 qts go in, 4 qts come out.
Reviewed by A-Rod:
I've been using Amsoil for years more people need to use it and stop buying cheap products!
Reviewed by Brian:
I love all Amsoil products very satisfied a longer duration before changing oil ever 6 to 7 thousand better than every 3000, with conventional oil.
Reviewed by Airwreck Nest:
Eliminates rough idle and extended change intervals beyond what a typical customer expects. I get great feedback from my customer base and it saves them money while protecting their engines with premium product.
Reviewed by walt:
From my work vehicles to my play vehicles I use Amsoil in them all for peace of mind
Reviewed by James Born:
Really like it!
Reviewed by Bobby Mota:
It's the only choice I make for my truck. Only down side is that not many local stores carry amsoil so to buy a top up litre is hard to find. I just buy one extra.
Reviewed by Bobby Mota:
It's the only choice I make for my truck. Only down side is that not many local stores carry amsoil so to buy a top up litre is hard to find. I just buy one extra.
Reviewed by J J:
Have switched to amsoil on our vehicles. Love the 15k mile change interval.
Reviewed by GRN:
I'm a new user of AMS products but am impressed with the ratings.
Reviewed by Olds455:
Not only do I believe Amsoil extends the life of my vehicles, the extended service intervals keep them out of the shop and me off my back for longer periods of time. When you commute long distances, like me, 3000 miles comes Way too quickly.
Reviewed by Lente Loquito:
I have been using AMSOIL since the early 1990's. Need I say more?
Reviewed by Nick:
Everything about this oil is great. I drive a 98 Toyota Camry that contains an engine toyota was sued over for its ability to make slude and lead to engine failure. Amsoil does not recommend using the extended drain interval (15,000 or 1Yr) with this engine however I only change the oil twice a yr putting on at least 7,000 miles per oil change. I had a 97 Toyota Camry with 280,000 miles with the same engine and the only thing that killed it was a car wreck. My current 98 only has about 140,000 and I expect it will last every bit of the 280,000 and beyond.
Reviewed by Teddy:
I had my 1964 Corvette project car all greased and lubed when I learned of Amsoil and then drained and replaced the oils and re-greased everything!
Reviewed by Vig:
Use it in my 2 vehicles, lawn mower. Great staff, only Amsoil!
Reviewed by MLH706:
I've used Amsoil Signature Series 5W-30 for years and will continue to do for years to come.
I first started using it simple as an avoidance to constant oil changes. Putting around 25-30,000 miles a year, it made more sense to change the oil once and the filter every six months, rather than wasting time changing conventional oil at every 3,000 miles. Many told me it wasn't safe to do so; however, I've never had any issues doing this.
First car...1993 Chevy Corsica 3.1L V6. 236,000 miles when traded. Engine ran perfect, car body rusting out.
Next car...1998 Subaru Outback 2.5L 4 cylinder. 263,000 miles before the body rusted apart.
Currently using in 2004 Subaru Outback 2.5 around 180,000 and Dodge Ram 2500 5.7 Hemi 130,000 miles.
As you see, long engine life with minimal time required for oil maintenance/changing, not engine issues, various engine sizes.
All of these vehicles have their oils changed once a year. Filters changed at oil change, and then again at six months.
Strongly recommend, especially if you like the simplicity of changing the oil only once a year or put many miles on each year.
Reviewed by Cadprof:
I have been purchasing Amsoil products for about fopur years now, everything I own that has a motor and transmission contains Amsoil products. Great products and a great price form a great company.
Will always buy my supplies here.
Reviewed by BIG BABA:
There is know beating AMSOIL. I have been using AMSOIL for 10 years and bank on how it is made and what it is made for. All their products are unbeatable in my eyes. Best mileage guaranteed and warranty no one can beat. Every car, truck, boat, big rig and more totally unbeatable for quality and service.
Reviewed by
TCS33:
Instead of changing oil and filter 3 times a year on my wife's 2010 Impala, I just change it once. And I am using a better quality oil and filter, when I use Amsoil !!! thanks
Reviewed by Mike:
I use thus product in my recently purchased truck. Mileage got better and engine ran smoother. I love it. I have been this product in mg last three used vehicles with outstanding results.
Reviewed by jg021v:
Oil change intervals last more than six months. I prefer AMSOil 5w30 Synthetic Motor Oil over any other. "True Synthetic."
Reviewed by MadMatt!:
got another 70000 miles out of it .I was sold been using it in every vehicle sence. When you do all your own service work yourself you notice where n tear on internal parts, and i've got to say the products from amsoil When you rely on your truck to make a living and cant afford break downs. You only put the best product in it. I've used other products in the past. but one slipping transmission and switched to amsoil products. Well offer the best protection i've come across "greasy" Hands Down Matt.S.
Reviewed by MadMatt !:
got another 70000 miles out of it .I was sold been using it in every vehicle sence. When you do all your own service work yourself you notice where n tear on internal parts, and i've got to say the products from amsoil When you rely on your truck to make a living and cant afford break downs. You only put the best product in it. I've used other products in the past. but one slipping transmission and switched to amsoil products. Well offer the best protection i've come across "greasy" Hands Down Matt.S.
Reviewed by Scott:
I run this oil in my truck and car. I swear by it!
Reviewed by Gary the Titan Beast:
I've been using the Signature series in all my vehicles for 5 years. I live in Alberta, Canada & it gets to -40 degrees Celsius never a problem starting & im so confident & I proved it with our 2002 Nisssn Xterra 15 years old & engine prob will go for another 15 years!
Reviewed by Rumpthump90:
I have bought amsoil 5w30 for all three vehicles I have owned, AMS has never let me down. I currently run this in my 2001 Chevy suburban with 180k miles and still running strong.
Reviewed by Marc:
Easy to use
Reviewed by Redidan:
I use this in two vehicles a 2001 blazer and 2003 silverado hd
Reviewed by Leeski:
I got in an accident a while ago. I got out of my truck to exchange driver information with the the other driver and noticed all the antifreeze leaking out of my truck do to the accident. When I seen this I went back to shut off the truck that was still running so the engine wouldn't overheat but the door was damaged and wouldn't open! My truck stayed running for over an hour with no antifreeze in it yet the temperature gauge didn't move, amazingly it never even came close to overheating. I owe it all to Amsoil''s superior oil that saved my engine! My truck is still running like new with over 380,000km! I'm a firm believer in the Amsoil line up and use it in everything that I own!
Reviewed by Chris:
Excellent product, helpful staff.
Reviewed by TOD UMBRELLA LLC:
Uses all the time
Reviewed by n/a:
Easy to purchase on line, which saves me a trip to the parts store, comparable in price with other quality synthetics, and it pours and looks good too. I use this product in a new Ford Escape with the 2.5 Eco boost engine, and have noticed an immediate small increase of 1.5 to 2 m.p.g. My only concern is about 20K oil intervals. Hopefully my on board computer will tell me when it's ready to change as well.
Reviewed by Paul:
Great product. Been using Amsoil for about ten years. My only complaint was the shipping charge. Amsoil has been running specials for preferred customers were they've been offering free shipping on orders over over a certain amount. When they offer this deal that's when I place my order.
Reviewed by Tyson:
I found this product and all the others produced by Amsoil are top quality, and found they protect my vehicle's and equipment that I run Amsoil in
Canada
United States
Long term use & I keep coming back
My car has 140k miles and I've been changing my ea amsoil filter every 10k miles (rated for 15k miles) and my oil in my vehicle every 20k miles (rated for 25k miles) without fail. Excellent results and cheaper in the long run when compared to other conventional products.