Extended Life Motor Oil

[GTP Dad]

Amsoil is also available on-line at Amsoil.com. Different grades of the oil cost more or less depending on the grade. I just purchased the signature 0W-30 for my son's jeep. The oil was $9.95 per quart and the filter was around 15 dollars. Total oil change cost was about $80.

[GregGP]

Originally Posted by BNaylor

How many miles do you have on your Grand Prix GregGP?

I would exercise caution switching to synthetic from dino oil with a high mileage engine or using extended performance synthetic. Many reports from SII 3800 owners about higher oil consumption and screwed up valve stem seals as a result and various seals or gaskets leaking due to old age, etc.

For a daily driver I'd stay with good quality dino oil. Most are good up to at least 5K miles now. Thats all I use in my non-modded Grand Prixs and other GM cars. I use regular Mobil 1 synthetic in my GTP.

Just turned 140,000 miles. I have switched it to synthetic already; I notice a little bit of a leak, but not much at all. What's the best dino oil to use? Or should I switch it back now?

[BNaylor]

Originally Posted by GregGP

Just turned 140,000 miles. I have switched it to synthetic already; I notice a little bit of a leak, but not much at all. What's the best dino oil to use? Or should I switch it back now?

Since you switched to synthetic oil with minimal issues then best to stay with the synthetic but not the extended version unless you feel safe going long intervals between oil changes. I'm not comfortable with that and replace the Mobil 1 in my GTP annually, regardless. Synthetic oils have special conditioners for the gaskets and seals and it sounds like yours worked out fine. The gaskets will leak sooner or later even with dino.

[GregGP]

OK. Sounds good. Thanks again guys, I appreciate the insight.