From my research I decided to try using synthetic and change my oil change interval to twice a year instead 3-4 times. To me the time/headache savings is worth the extra $20 a year.

I've never experienced an oil related failure in any of my cars, since I have always been pretty good at chaning it in the 3000-5000 range. I always used a good quality dino oil, but have been using Mobil 1 full synth for three years now and will not likely go back. I have most definitely noticed a smoothness difference in the engines of both my vehicles and have also noticed that they are both cleaner internally than before.

I won't stoop to argueing with anyone who maintains that dino is good enough, since it really is "good enough". I just choose to pay the difference, since I expect more miles from my cars and trucks than many.

BTW, I buy my synthetic at Walmart. 5 qts for under $23 for Mobil 1. Add a good filter and I still spend less per oil change than the average 10-minute oil change drive-up customer, by doing it myself.

Out of any mentioned in this thread, Mobil1 is the scam, with the new base stocks they've been using. Don't believe me? Try looking around at the forums on www.bobistheoilguy.com.

That said, any decent oil in the proper viscosity with a quality filter will take the 3.8 as far as any of us will ever need to go on an engine.

Would that be the #51040_?

Mobil 1 user w/ the AC Delco PF47. I am due for a change Saturday. It will be my first time letting it go to the 5,000-mile interval. I used to change it every 3K.

Ive been running AMSoil because I get an awesome discount on it at work, however...I have been running mobil 1 in the Alero for whatever reason, convience that I dont have to order it in i guess..and I can say, that engine is spotless inside. Just keep up with it, 5000 miles..thats your best bet..I normally run the Delco PF-47c filter as well..

I wonder if running full syn for gas mileage would pay off with-in town driving? :?

I use Napa Premium oil and their Napa Gold 1040 filter. When doing a trip, i.e. WCBF, then defintely full syn.

I have use Vavoline, Castrol and Mobile 1 full syn and I have had no problems with any of the 3.

Just my 2 sense

I change it every 3 months. If it only has a thousand miles on the oil; I still change it out. I bounce back and forth between regular dino and syn blend. Lately I've been running 3 quarts of 10/30 with 2 quarts of 10/40.

Probably not.

Personally, driving style has more to do with time between oil changes than a hard number. I typically change oil at around 7000 miles. But I drive about 200 miles per day, nearly all of it on the interstate cruising at 75mph, 2200rpm, 15 inches of manifold vac. Never had any problems with oiling on any GM motor ('90 Bonnie included.) using plain old dino oil and a decent filter (no HP oil filters or additives..just a plain off the shelf replacement filter.) Just keep an eye-ball on the oil pressure.

The '90 Bonnie hit another milestone yesterday. It just rolled past 70,000 miles. At this rate, I'll have trippled the milage on the car in one years use.

A 1990 Bonneville being driven 200 miles per day and only having 70,000 miles on it. Something don't add up. :P