Type of Oil to use for Final Drive/Rear Diff?

[munkeeboi83]

What type of Oil to use for Final Drive? I did a quick search on the forum and didn't really come up with anything.
(1980 BMW 528i, 5spd manual)

According to the Haynes manual, I need to use Castrol Hypoy (SAE 90). Seems like all the local auto parts places have only 80W90 or 85W90. Would it be okay if I used 80W90 (API-GL4) or 85W90 (API-GL5) instead since it's readily available? I think I need something with a API-GL5 I just don't want there to be any problems to arise.

I saw that this is pretty popular online. Where would I be able to get it in SoCal?
http://www.autobarn.com.au/products/10/70/4214481/

Castrol Hypoy LS (SAE 90)
Only found it available on the Castrol UK website
http://www.merlinmotorsport.co.uk/m17/C ... _info.html

I'm very lost right now. Don't know what to do. =(

[mcibmw533]

I know many of the BMW faithful like to use red line products and their website is fairly useful.

Check them out at the website below. They even have a dealer lookup function, but verify the shop still stocks their products (several of the dealers listed local to me have since gone out of business).

http://www.redlineoil.com

BMP also stocks their product & I believe they give BMW CCA members a 10% discount which may offset shipping charges.

Hope this helps.

Micah

[T.Hanson]

Go to Napa, O'Reilly, etc., get a gallon of 80 /90 gear oil and a plastic pump w/clear plastic tube. Like Valvoline.

Drain the old, add new. Fill until it runs out the fill hole while adding.

Next year if you want to feel wonderful, do it again.

You can feel wonderful reading and buying other stuff, but the above has worked for me for twenty years, four cars, no problems.

[Mike W.]

For the diff you want a GL5 oil, not GL4. Aside from weight, GL5 is stickier, which makes it better for diffs, but not so good for synchros. Weight of the oil is less important than the GL rating, I go with 75-90 synthetic these days, but a GL5.

[munkeeboi83]

I went with what you guys told me, I used regular 80W90 (1 bottle of Lucas + the rest 1 bottle of Valvoline). Lucas sure does seem pretty thick. I think the oil was API-GL4 though. I might have to double check that. =( The car seems to be running a little bit better. The fluid I drained out was pretty dark and burnt out. I think a good amount of it might have leaked out too. =(

I used the small little hand pump attached to a Costco Listerine bottle that I filled up with oil and that provided a easy solution to fill it up without making a mess. I didn't get 80W90 oil all over my eyes this time. =)

FYI: the Final Drive drain plug and fill hole uses a 10 mm allen key or hex bolt. I don't know who I saw on the forum that kept on saying it was a 9mm bolt. lol

Sorry I don't have any pictures, can't find my camera. =(