Hi guys, I'm looking for some advice. Im currently running an 89 c4 with 111,000 miles. Im just about to change the oil. The last owner was running Mobil 1 10w 40 but I've noticed a little oil loss although temps and pressures are good. Im guessing the engine has a little wear and the seals are not as tight as they once were. I am in europe where the temp range is usually 35 to 80F. Would It be better to stick with the 10w 40 and add an oil additive like Lucas oil stabiliser or move to a classic car oil in 15w50 or 20w50. Also can anyone recommend a brand that's available in Europe.