I've got a '79, and its oil change time again. What's your preference for a 308?
I use valvoline synthetic 20w-50. Some people like redline. Find a quality, synthetic and you'll be happy. So will your car.
I harpooned a whale a few years back... Now whenever I need to change the oil, I just throw a little blubber on the fire.
I use either Valvoline 20W-50 Racing Oil if I can get a good deal on it by the case, Castrol GTX 10-40 if I can't.
Because the engine oil gets changed every 2000/2500 miles I use Valvoline VR1 20w50 Racing Oil. Can't see the justification of going to a synthetic when it isn't in the engine that long. I DO use Red Line 75w90NS synthetic in the trans axle though. The shifting is way better than with dino oil. DJ '78 308 GTS
I posted this question regarding my '72 Dino at bobistheoilguy.com, and after much discussion and reading I concluded that Mobil 1 15W-50 is a good choice. These older cars need a 50 weight oil and the 5W-50 oil is not as good because it's too full of viscosity improvers at the expense of wear reducers. Redline, Amsoil, etc would be fine too but more expensive. My plan is to perform an oil analysis at 1 year to see how it's doing.
It's been well documented (well at least to me), that running synthetic oil in older cars that have traditionally run dino oil can cause some serious, irreversable oil leaks. This is particularly true on the Porsche 911 engines, as they tend to expand quite a bit when hot. I don't recommend using synthetic on any Porsche air-cooled engines, unless they were recently rebuilt with new seals. Here's a link to some threads I dug up: http://forums.pelicanparts.com/search.php?s=&action=showresults&searchid=597276&sortby=lastpost&sortorder=descending -Wayne
Kendall GT-1, 20w50. Been using it for years in Air-cooled motors: Porsche, VW, BMW M/C's...'Alfa of Tacoma' recommends it for the older F-cars. Like DJ, my oil is lucky to see 2000 miles, and I drive the car reasonably. We should get together and market this hardly used motor-oil for lawnmowers and such..."Pre-owned Ferrari Oil!", recycled for your high performance John Deere! I don't think any of us would use poor quality oil, so the performance characteristics I suppose shouldn't vary that much in dino oils. But here's a question: What is the differentiating quality or the performance "cut-off" that deems some oils worthy of the "API Star" recommendation, while others don't get it. For example, Castrol 10w30 GTX has the "API" star on its label, while Castrol 20w50 GTX does not. Obviously, the viscosity improvers must play a role in this differentiation, but is there more to it than that?