Quote Originally Posted by repeated_love View Post
I got into an argument over engine oil.

I wanted to buy the Magantec 10-40 for my 94 Accord Exi but was told as it has done over 100k I should get 20-50. I ended up getting Valvoline 20-50 but could I have still gone with 10-40?
From my experience, it really depends on the health of the engine.

10 years ago I owned a DA1 integra. I got it with 210,000kms, and had to run minimum 25W++ oil to avoid it burning oil up like crazy. The engine was already loosing some compression when I bought it, as discovered during a pre purchase test. The piston rings were worn.

Now I own a DC2 Integra. 185,000kms now, last compression test came back entirely good and within factory specs. I use Valvoline 10-40w Synguard in it and it runs very smooth.

The previous owner's last service was with a regular Ultratune shop, done only 2 months before I took over the DC2. Whatever oil they put in the engine was crap, because it made the engine rev all rough and lumpy. Noisy too. Maybe the shop thought engines above 100,000km must use 20w and up oils or something.

I swapped the oil out with 10-40w Synguard a week after I bought the DC2, and the difference in smoothness was dramatic. Besides, the DC2 was specced to run with 10-40w oil in our weather conditions from the factory.

Moral of the story? Don't let mileage determine what oil to use. Let the health of the engine do it. If the engine's compression checks out fine, stick with the original factory specs in oil weightage.