Fellow mu-X owner here! If you're thinking about upgrading from the standard Isuzu Genuine Motor Oil 10W-30, check out the ZIC X7 Diesel 10W-30 Fully synthetic. I used Amsoil Turbo Truck 5w40 too (10k km interval) but it's expensive for my Garage queen mux haha. Mobil Delvac1 5W-40 is good as well.
I really liked Valvoline, good quality, reasonble price.
Valvoline Restore & Protect or Pennzoil Ultra Platinum are also great oils to run and clear up and baked on sludge.
Buy Valvoline oil, and maybe it's a good time to switch to 5w-30 in it.
I have Signature in my 25. Smoothed out the engine noises quite a bit.
Engine noise is a little, well noisy, mine is less rumbly/vibrationy after I changed my oil and used Amsoil Hybrid oil. I can’t generally feel anything when the engine kicks on now, before I could definitely feel it every time it kicked on.
I only run Valvoline VR-1 40-wt in my air-cooled VWs
I tell you the stuff really works. My 2009 Matrix used to burn oil before I switched to Valvoline Restore and Protect.
My last [Blackstone-labs.com](http://Blackstone-labs.com) report came back with 1.8% fuel dilution. 2021 1.5T at 23kmiles, 6800 miles on the oil (0w20 Valvoline R&P).
I use that Valvoline, sometimes throw in random fully synthetic oils I get in bulk from an auction. I feel like it contributed to a rear main seal leak. Thinking of switching to a 5w40
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If choosing engine oil across many manufacturers, check the part ranking. If your choice is down to two brands, the PartReview part comparisons help.
We compare engine oil across these categories:
In March 2026 on PartReview, engine oil AMSOIL and VALVOLINE were roughly equal.
In March 2026 on PartReview, engine oil AMSOIL were overall more popular than VALVOLINE.
By vote balance, engine oil AMSOIL surpassed VALVOLINE:
By number of reviews, engine oil AMSOIL surpassed VALVOLINE:
In March 2026, according to PartReview, engine oil VALVOLINE led more car-specific ratings than AMSOIL:
VALVOLINE are chosen by owners of cars such as: Ford Fusion, Hyundai Elantra, Kia Soul, Toyota Prius, Toyota Yaris, and others.
AMSOIL are chosen by owners of cars such as: Honda S2000, Toyota 4runner, and others.
If this comparison didn’t fully answer your question, there are many others on PartReview.
For example, comparisons of engine oil VALVOLINE with: Mobil, Castrol, LIQUI MOLY, MOTUL, Shell, PENNZOIL, RED LINE, OEM Toyota, Mannol, RAVENOL.
Also available: comparisons of engine oil AMSOIL with: Mobil, Castrol, LIQUI MOLY, MOTUL, Shell, PENNZOIL, RED LINE, OEM Toyota, Mannol, RAVENOL.
You can also see who is better among other engine oil manufacturers: Mobil or Castrol, Mobil or LIQUI MOLY, Mobil or MOTUL, Mobil or Shell, LIQUI MOLY or Castrol.
