How long between oil changes?

[jason]

Hi Bob,

Welcome to fatherlarrys corvette shop. I'm glad to meet you.

I was wondering, on my '99 hardtop c5, it sits in the garage all winter and I just may put about 500 miles on it in the summer. I don't race it and I drive it nice and easy. I know on regular oils they say you should change the oil every six months, even though you don't use the car. Does that stand true with the Mobil 1, and how often should I change the filter? Thanks.:wave:

[Robert Pache]

The normal change interval for your year Corvette is 10,000 miles or once a year, whichever comes first or at the computer change indicator. Mobil 1 5W -30 is the factory fill for Corvette and meets their 4718M spec. In your case, once a year is satisfactory, in fact, I understand that Corvette is considering a two year drain cycle for seldam driven Vetts when using Mobil 1 or equivalent. However, condensation can accumulate during storage, especially during winter months. The oil you drain is still good but you cannot get rid of this moisture until a period of continual over the road driving. Make sure you use the new Mobil 1 with super syn, it is an improvement over the former API SJ version, Meets SL and is far superior to other competitive oils marketed today. Use either 0W-30, 5W-30 or 10W-30 grades, all meet the GM 4718M specification.

Bob Pache
:)

[jason]

Great info! Thanks for the tip on the super syn. I think I'll change it every six months to be on the safe side, considering the moisture build up like you said.:nod:

[TopVette]

Bob,

How much better is the super syn? Will I see a difference in my oil pressure? Thanks.:)

[Robert Pache]

I doubt that you will see any pressure change with the new Mobil 1 Super Syn formulations since this is dependent on the specific vis grade and its shear stability. While the addition of Super Syn will increase base oil VI, it will not likely be noticable in oil pressure. The Super Syn does improve oil film strenght, especially under high pressures hydrdynamically lubricated areas such as piston rings/ cylinder walls and even to a certain extent, cam/lifter. Rod and main bearings are relatively low stress areas where an adequite fim layer is maintained. Also, the new Mobil 1 has been reformulated to meet virtually all world automotive performance requirements and has been approved to Corvetts 4718M specification.

Bob.

[TopVette]

I was reading an article where someone changed their oil and filter with a different brand other than Mobil 1 and the GM filter and their oil pressure changed. The dealership he had brought it to checked the oil pressure by bypassing the dash gauge, eliminating the possiblity of a bad gauge, and the external gauge read the same as the dash gauge. He went back to using Mobil 1 and the GM filter, and now his oil pressure is back to original. It could have been the filter or the oil that the dealer used. What do you think? This is why I asked my original question. Thanks Bob.

[Robert Pache]

I cannot really say what the problem was. Perahps it could have been a bad filter with a faulty bypass or excessive fine filtration or it could have been an oil with excessively low viscosity. It might have even been the wrong filter application. Only by analyzing the filter and oil could I give you a definitive answer. Unfortunately I am no longer in the lab to answer these questions.

Regards

[TopVette]

Thanks Bob, I didn't mention it but the way it was explained was that he changed the oil himself, and put the AC filter back on. Then after he changed the oil the second time with another AC filter the oil pressure came back up. So who knows, it could have been the visocity like you said, or the filter, but what makes me think that it was the oil, is that he put a second filter on, after the second drain and then the oil came up. Well, your the chemist, thanks for the help in satisfying my curiosity. By the way, will you be at Carlisle? I'll be there with Father Larrys group.

[Robert Pache]

No, I have no plans to go to Carlisle.