1999 BMW 318 Transmission oil leak

ESPEN

MEMBER
1999 BMW 318
4 CYL
2WD
AUTOMATIC
210,000 MILES

The transmission seems to have a small leak somewhere as there is reddish oil on the garage floor - a few drops per night only. This has been leaking for a few weeks now.
I have read forums etc and topping it up and checking levels seems to be a nightmare as it must be done via filler plugs etc.

However tonight I noticed a little plastic reservoir below the air filter which says ATF oil only. I unscrewed the lid and inside is red transmission fluid.
The plastic cap has an internal hollow rod attached with two markings on it. Presume fluid level must be bwteen these marks - it is a bit lower though.
Is this where I can top it up and must the temperature be between 30 and 50 Deg C to gauge the correct level.
Also what fluid is recommended

1 Reply

SERVICE WRITER

MECHANIC
9,123 POSTS

Fluid type GM trans:

Fluid type ZF trans:

If you can get wolf's head universal synthetic trans oil, it will probably be fine:
http://www.wolfshead.com/specsheets/universalsynthetic.pdf

Check the color of your coolant, by description it may be coolant leaking, but I can't see what color it is from here ;-)

That is the location to top it off. The temp is critical. If the trans fluid is too hot, it will be fully expanded and topping under this circumstance will leave the level low.