I purchased a new SKF 13978 oil seal from Rockauto but when I fitted it today it literally just slid in without giving much resistance at all. Now the manual says to use an oil seal drift so there should be some resistance when installing it obviusly to ensure that there is a good seal so I'm a bit concerned. I've double checked all the part numbers and this seems to be the right one. Has any one else experienced this issue - any advise please?