transmission fluid

**rags1986** · February 25, 2021, 02:08 PM

I just had the trans in my Atom 2 replaced. i sent it in to have the trans rebuilt since I lost the synchros for 2nd gear. My mechanic was able to source a brand new GM replacement unit for the same price of the rebuild. However we ran into an issue when it came to fill it up with fluids. The literature that we received indicated that the fluid used in it was a Saturn Manual Transmission Fluid. (part number 21018899 No longer available). My mechanic spoke with one of his suppliers who indicated that part number was superseded by 88861800. He wasnt able to source either of the fluids so he looked online at aftermarket fluid companies, and typed in the original part number 21018899, Royal Purple recommends HPS or XPR5W30. The first is a 75w/140 gear oil, while the other is 5w30 synthetic oil--these are quite different viscosity fluids so he checked some other sites. Some mentioned Dexron VI which is synthetic automatic trans fluid. When they had drained my original trans they noted that the fluid had the appearance of an automatic fluid (red and low viscosity). Has anyone with a Brammo GM Ecotec 5 speed car changed their trans fluid recently? if so, what did you use?
Any input would be appreciated.

**Lane** · February 25, 2021, 06:51 PM

When I last replaced my fluid more than a few years ago, I had done some research and it looks like the Getrag F35 trans was shared with SAAB. See post #2 in this thread - I'm not sure it's useful, but it may give you a point in right direction to identify what SAAB owners are using these days. I had bookmarked a few references to SAAB part 93165290 as a possible equivalent fluid, but you'd have to verify that.

Crate Engine Depot has this which it says replaces Saturn part # 21018899.

Good luck! Let us know what you find out.

**sector: 4** · February 25, 2021, 11:26 PM

https://www.amazon.com/Genuine-21018.../dp/B00BK7M1EU

https://www.ebay.com/itm/Genuine-GM-...-/402009926997

https://www.gmpartsgiant.com/parts/g...-21018899.html

https://www.cobaltss.net/forums/driv...thread-230048/

**rags1986** · February 26, 2021, 07:25 AM

Sector 4 and Lane thank you for your info this was very helpful. Will let you know what we are able to source. Interesting to note that I googled F35 transmission fluid and found some other useful links. One of which was

https://dfkitcar.com/forum/index.php...on-fluid.1702/

On it the following question was noted: Does anyone have a clear answer as to which type of transmission fluid is needed for the f35 with LSD out of an 07 ss cobalt ? I found a tread stating it was gear oil equivelent to a 75-90 weight but when i got a brand new trans and went to fill it up thin red fluid came out that looked to be Red ATF.

was interesting to note that they also had the observation that the fluid appeared to be a red ATF.

**CORNER CARVER** · February 27, 2021, 11:01 AM

The 88861800 is a good GM number that should be available thru any GM dealer or alternate source. From my understanding its a modified form of ATF fluid tailored for manual transmissions and transfer cases.

MADMAXATOM recommended a Ford fluid XT-M5-QS it is full synthetic MTF fluid. i have yet to change it into my Atom but it helped with shifting issues in my 04 CTS-V and the V calls for the 88861800 in the GM service manual.