question about mixing synthetics w/mt??

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Nov 3, 2018 | 02:04 PM

#1 (permalink)

dohcfiend

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Joined: Sep 2018

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From: VA

question about mixing synthetics w/mt??

I think I read this trans calls for 70/80 from mb but was curious about mixing to get the best of both worlds. for example gm synchromesh is considerably lighter so if I went 1.7L factory to 0.3L synchromesh............I am assuming once it heats up they would mix bringing it to like a 63/75 or something but when it sits and is cold would the lighter oil separate and go to the top?

i.e. when cold it would be utilizing the lighter oil since it is on top then mix with the heavier oil when warm??

thanks in advance

Nov 3, 2018 | 03:15 PM

#2 (permalink)

waldig

Senior Member

Joined: Feb 2008

Posts: 4,508

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From: VA

Re: question about mixing synthetics w/mt??

ITS OIL, the syn is more stable, no magic chemistry, use and enjoy. Woody

Nov 3, 2018 | 05:21 PM

#3 (permalink)

onehundred80

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Joined: Apr 2006

Posts: 25,432

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From: Ontario

Re: question about mixing synthetics w/mt??

Quote:

Originally Posted by dohcfiend

The manual states MB approved 5W-30 oil for the manual transmission. The viscisities you mention are for differentials. Using those oils in the gearbox would be really wrong.

Nov 3, 2018 | 08:12 PM

#4 (permalink)

pizzaguy

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Joined: Jun 2009

Posts: 13,975

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From: Fort Worth, Texas

Re: question about mixing synthetics w/mt??

I ran Mobile 1 5W20 in my Graphite (on recommendation of John Moorehead and John Tlika, who both tried it) and I found I got smoother shifts.

Nov 5, 2018 | 07:45 PM

#5 (permalink)

harbor

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Joined: Dec 2004

Posts: 1,251

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From: Rochester Hills, MI

Re: question about mixing synthetics w/mt??

Crossfire manual trannys had a factory fill of ATF fluid while the identical tranny in the MB SLK 320 came with 75W80 manual trans fluid.
The DaimlerChrysler owner’s manual allowed 5W20 motor oil as a substitute (although syn wasn’t specified), while MB lists no alternative to their factory fill.
75W80 or 90 trans fluid has a similar viscosity to 5W20 or 30 motor oil - See forum member Kamilspider's Kinematic viscosity chart in the below link.
The Franken-brew mixture you are considering would probably be OK, but there may be some other additive issues/clash with the mix. I think you’d be better off using one fluid. See the below thread with the imbedded links, and see if that helps your decision making.

https://www.crossfireforum.org/forum...-question.html

Last edited by harbor; Nov 5, 2018 at 09:56 PM.