View Full Version : Engine Oil?

01-13-2005, 10:04 PM
Just bought an 87 GN up here in Canada. I am 21 and have been looking for one for 4 years :) Could not find a proper thread for fluids so I put it here. Car has been running on GTX 10w-40 its whole life. Should I switch over to a synthetic motor oil? She has 85K miles. Runs strong. GM mechanic told me if I switch over I cannot go back as it is like mixing vinegar and water. Is that true? But why would I want to go back if synthetic is that much better. Any help would be appreciated.

01-14-2005, 12:57 PM
Lots of myths and half-truths about oil out there ... a good FAQ can be found here:


A good quality dino oil will work fine, but you need a narrower viscousity range than 10W-40 from all the advice I've seen. 5W-30 or 10W-30.

The newest oils seem to have eliminated a lot of the Zinc (antiscuff) and such, since they are considered a hazardous waste and a lot of modern engines now run roller lifters. The synthetics seem to better with this and have better temperature resistance too.

Some of the synthetic blends get decent marks from a performance standpoint, but for a couple extra $ in an oil change, I'd just go full synthetic.

If you watch, often times the large chain stores (Target, Kmart, Wal-mart, etc.) have a big sale on synthetic (most often Mobil One or Valvoline synthetic), which makes it less of a cost difference.

A good filter is important (Wix, Delco Ultra, etc) ... I personally stay way from the Fram.


01-14-2005, 11:08 PM

Thanks for the interesting reads--great information, I am new to these cars and trying to learn as much as possible. I have decided to switch to the synthetic. The positives outweigh the costs. But which to use? Spring cleaning recommends 5w 50 synthetic, others recommend simple 10w 30. Which to choose? I bought a stock AC delco PF 52c oil filter, is that compatible with a synthetic oil? Do all AC delco oil filters have an anti drainback feature, such as the ultra series?



01-15-2005, 11:45 AM
Any of the brand name synthetics usually have extended viscousity ratings ... 5w-30, 10w-30, 5w-50 should all work fine. Use the "lighter" weights if the weather is cold.

01-17-2005, 01:13 PM
I'm running mine on Amsoil 10W-30 year round, I highly recommend a good Synthitic oil!