Customer Ratings & Reviews

I only use American AMSOIL in all my vehicles. For this one, I use it in my 2005 Honda Fit 1500cc..

Why is it when I change my oil does my mileage drop by 2mpg. For the first 400 miles 1 1/2 to 2 mpg less then it creeps back up.

Awesome cold start protection, and anti-wear lube, simply the best

I started using AMSoil in the mid 80s while in Alaska. Cold extreme make lubrication very critical. At minus 40, most petroleum lubes won't even drip off the dip stick and when started cold you can hear every bearing in the engine as there is little or no lube flowing. No so with my AMSoil.

I've been running 5W30 Signature Series in my 2002 Tacoma since putting it on the road in 2016 with 116,000 miles on the engine. I have since had Oil Analyzers (Amsoil, Inc.) test three samples from the truck so far, and have yet to have the oil last more than 13K miles before being told it's time for it to be changed. So much for the 25,000 miles/1 year claim...

This review is about all Amsoil Signature Series Motor Oils that I use: 5W-50 (2013 Mustang Boss 302 26k mi), 10W-30 (2001 Jeep Cherokee 4L, 296k mi.), and 15W-40 (2003 GMC Sierra 6.6L Duramax Diesel, 305k mi). In all cases I use the respective EaO oil filter. I change oil & filter at the following intervals: Jeep 7k mi., GMC, 10k mi, & Mustang Boss 302 5k mi or 1/yr. I owned a 1990 Jeep Cherokee I bought new, after 12k miles I switched from Castrol GTX to Castrol Syntec motor oil. Continued to change oil and filter (Fram Tough Guard) every 3k miles. At approximately 140k miles I removed the valve cover to replace gasket and got angry at what I observed. The valve train had heavy sludge built up! I Sold the 1990 Jeep at around 160k miles. Purchased a used 2001 Jeep Cherokee Limited 4L with approximately 80k miles from a used car dealership. Went to a local store that sold Amsoil products and purchased the 10W-30 Signature (or equivalent name series available in 2005) and the EaO filter. Religiously changed oil every 6.8k-7.5k miles. At approximately 160k miles needed to replace the valve cover gasket. The top of the valve train looked as if it were new! I even put a small rag on the end of a lifter puller so I could reach down in a depression beside a lifter, no sludge! About 20k miles later I had to drop the oil pan to replace the rear main seal, other than a thin film of residue in bottom of oil pan, the crankshaft, connecting rods, cylinder walls, etc. looked great. BTW, this engine uses less than 4 ounces (1/8" on dip stick) of engine oil every 7k miles. I don't care what anyone says about any other similar product, as long as I see these kinds of conditions with low wear and oil consumption Amsoil will be what I use if they have a product that meets or exceeds specifications. My Boss 302 has all Amsoil fluid except in the 6 spd manual transmission, if or when they have that available the Royal Purple is getting drained and replaced with Amsoil.

Love the extended oil change intervals and my fuel mileage increased slightly, which leads me to believe it must be lubricating everything very well.

I have 2 vehicles that have had this oil in them (changed every 15,000mi) since I bought them new. They both have mileage approaching 250,000, and they run like BRAND NEW. My newest vehicle is a 2017 Subie Forester Turbo so it gets Signature 5W-30 every 10,000 miles, and I'm sure it will see 200k and beyond.

It's great year round hot or cold

I have used Amsoil for 30 years and wouldn't think of using any other oil.

I use Amsoil exclusively

I have been using Amsoil for over 15 years and have never had a problem, it's a well proven product that I trust in all of my cars for work and for pleasure. I will will continue to use Amsoil and benefit from it's proven results! I own a Livery/Limo Service and I drive about 40-50K miles a year on various cars and I believe Amsoil is the best Oil for all of my vehicles. With the long 15k Mile change intervals it is a money saving gem and your engine benefits 100%. I recommend there products highly!

Used in my F150 exclusively. Excellent oil & filter. Would not use anything else.

I've used this brand and series in my Dodge Ram 4.7 v-8 since I acquired it at 90,000 miles. I've driven another 70,000 miles since and the engine is stronger than it's ever been! I expect to drive this truck until at least 300K miles because of the Amsoil Signagture Series Synthetic brand motor oil. I won't use anything else!

#1 for 3.5L ecoboost

I like being about to change oil at any time between 5-10k and not have to worry about weather or not the oil is doing it job !!!

Several years ago I switched to Amsoil in my GMC Yukon. I was very impressed with what the Signature Series 5w-30 Motor Oil looked like after the first oil change. With all the oils and products that Amsoil offers, I have since switched everything I own over to Amsoil. Even my lawnmowers.

Love that you don't have to change oil as offer as regular oil. Is is a little high. Hey but you get what you pay for.

This is the best oil money can buy in my opinion. I use this in all my vehicles and have for the last 12 years. Love only having to change the oil once a year. I highly recommend this product.

Instant satisfaction, after the first start up i could already hear and feel things running smoother.