Engine oil & Diff Fluid

[8ti9ine]

Hey everyone just bought a 89 325is, and I want to do some service to it, I'm a firm believer in Castrol motor oil, but what viscosity should I use for a motor that has a 130,000 miles on it? It has according to the vin# a 3.73LSD, what type of fluid do you recomend for the rear diff? & Synthetic or Reg. gear oil W/an additive? Any suggestions would be much appreciated.

[Reuvers]

just did a search and seems like people here run 10w40 in winter and 20w50 in summer. Might help?

btw your your local parts shop will be able to check this for you easily in their computer when given your license plate

[yammahamma]

in my 89 325i with 170k miles I ran 5w30 full synthetic Mobil 1 and in the diff I don't remember the weight but I also did full synthetic Mobile 1 with an additive because without it, my diff would make a rubbing/grinding noise when turning a sharp corner at low speeds. The additive fixed that...I don't remember the name but I did buy it at autozone.

Sorry for the lack of details, it's been a few years. Hope that gives you a little help though.

[german-speed-demon]

5w40 synthetic here, been run that way for the last 10k miles.

[8ti9ine]

Thank you for your suggestions!

[Rfitz25]

Redline Diff and MTL in the trans check thier website must get correct fluid for LSD diff or screwed

[8ti9ine]

Much Apreciated