Re: Synthetic ATF? (archive)

I used Amsoil in my 528e & will change my 735 to Amsoil when it's due. Dexron III is a synthetic blend which extends the breakdown temp. by approx. 50 degree(F) beyond Dexron II. Amsoil is good for 100(F) beyond Dexron II, with heat being the primary enemy of an automatic. I consider Redline to be equally as good. I have an Amsoil dealer just down the street so that makes it convienient.

As for draining the torque converter, you can undo one of the cooling lines at the radiator and let it idle in park until it starts spitting. Be prepared for a mess! I've also drilled & tapped a small hole (6-32) in torque converters in the past, and epoxied (JB Weld) a panhead screw to seal it when done, but do this at your own risk. If a loose metal chip found its way to the valve body, there would be no end of havoc. With BMW's 4hp22 having a history of failing while idling, cracking the line & letting it pump out is a risk as well. I don't recall what year the factory routed an oil line to the bearing to correct that defect but I think it was in the 80's

When you refill, do so slowly lest it overflow out of the vent cap (3hp22 is a problem this way, don't know if 4hp22 is).

Regardless, do not hesitate to use full synthetic

gale
92 735i 142K

I need to replace the fluid in my automatic transmission. I was thinking of replacing it with synthetic fluid (Red Line). I'm assuming I should pump out the torque converter to assure I get all the old fluid out. Does anyone one have any comments on using synthetic ATF? Is there a preferred brand? Thanks for any advice!

- John

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