Hi all! I know this has been discussed various times before but I couldn't find a definitive answer as to what the best oil for my car is. As you can see from my profile I have a W124 Pre facelift 1990 230E Saloon Auto. I am currently using 10W40 as I have been for the last 3 services I have conducted and have not experienced any problems, however I just want to know what the best engine oil would be for my car as I have heard things like Mobil 1 synthetic etc... The miles are getting on and I dont want to make a wrong move on oil picking so best to ask you guys! The car is on 167,000 Miles now... no oil usage leaks etc.. M102 engine.. all good "touchwood" ! Is it worth me changing to a full synthetic oil Mobil 1 or just keep on 10W40? Im kinda lost as some say its good to change to thinner oil as the engine gets older, but others say stay on the same ??? Any ideas would be kindly appriciated... Thanks!