Triumph Repair/Spitfire 1500 Oil
My wife's dad had a 1964 Austin Healey Sprite and he has convinced my wife that it is unwise to use American Oil in her 1979 Spitfire 1500 because substances in American oil will degrade the British gaskets, is this true?
No, Oil companies change the chemicals they add to oil all the time but I never found any that affected gaskets nor seals.
The one thing I can tell you about oil is to NEVER add a different brand of oil to the oil in the engine. This can be very dangerous to the engine because each oil company uses many different chemicals to add features to their oil and the oil companies' chemical engineers don't know what substance this makes when these chemicals are mixed.
Change your oil and filter together and at about every 2000 to 3000 miles. Warm the engine up before you drive it especially in the winter as the oil when cold does not get to places in the engine where it is needed when the oil in cold. Don't listen to any oil company adds that tell you it is ok to run their oil for 5, 6, and 7000 miles before changing their oil.
You can't ware oil out but the problem is contamination and oil filters can't clean the oil well enough.
The only oil I don't recommend is Castrol Syntec. You can read my web site as to why.