pakman

Today I took my truck in for having the diff service done before I start towing cross country. In looking through the records for maintenance done last year at another dealer the service rep discovered that the other dealer had put in regular 90 grade diff oil in my front and rear diffs and transfer case. The service rep verified that my truck diff needs synthetic diff oil by checking the Dodge computer data base by putting in the VIN number for my truck.
So my questions are:

1. What type of damage could I have done to the truck diff while towing with just 90 grade oil?

2. Now that the dealer put in the synthetic diff oil, is there an issue of "contamination"? with the residual 90 grade in the diff?

3. Does mixing synthetic and natural lubricants cause an issue?

Thanks

XLR8R

Well, certainly not a "best practice", but I wouldn't worry about it.

Good for you for discovering the oversight and correcting it!

bigdav160

Ease your mind. The answer to your questions are:

1. None

2. No

3. Not at all

I would worry about gear oil in the transfer case. I believe it should be ATF

rockcrawler304

This would be my concern as well. I hope you had a typo for the transfercase. Probably no harm done but if it was built to use ATF+4 it should have it. The different gear oils in the diffs are not anything to worry about.

mrblond

Im considering running 15w 50 mobil one in my xfer case, should be thin enough for the pump but I think in the old days xfer cases aways used 90w gear lube.

SOhappy

That was the first mistake.

pakman

Thanks to all who responded. Going back in tomorrow to have leaking power steering gear box replaced. Wish me luck

The Pakman

XLR8R

Make sure they use ATF+4 in the PS pump...