Originally Posted by shertex

One car has 96,000 miles and has never had the differential fluid changed. The other car has 228,000 miles, had the differential fluid changed with the regular stuff at 150,000 miles, and has a slow leak.

Do the cautions about switching from conventional engine oil to synthetic also apply here....that, if there is a leak or crud plugging a leak, synthetic will make matters worse? I'm partial to synthetics, but am fairly confident I don't want to mess with the headache of resealing a differential if I don't have to.

Thanks.