The 2005 TL says to replace the manual transmission fluid once every 30,000 miles. But what if I've put in the GM Synchromesh Modified MTF? Do I stick to the 30,000 mile schedule? Or do I have to alter it? Thanks.

 

I just had my GM Synchromesh FM MTF tested after 50,000 miles of use by Blackstone Labs. The results showed some viscosity thinning and somewhat higher than hoped for iron and lead wear. Based on the results, I'm going to reduce the next fluid change interval to 25K miles.

 

Nice. Was there anything else interesting in the test? There has been lots of fear among members here about horrible things the GM fluid might do. Sounds like nothing "horrible" is going on. I even waited and watched others for over a year before I finally started using the GM fluid and have kicked myself every since for waiting so long.

I had figured I'd do a shorter interval than 25k and was figuring 15Kmi since it is relatively easy for me to do at home. 25kmi equates to a few years for me. Even better.

 

Nothing horrible at all. But it's obvious that 50K miles is too long to leave this oil in.

I sent in two samples to Blackstone, a 50,047 mile sample and a virgin oil sample. Blackstone read my information sheet wrong and listed my car's tranny as an automatic so their comments are off. I need to rectify that with them.

"We found above average iron and lead in the first sample from your transmission. These wear metals point to excess wear at your clutch plate and show that it was time to change this oil. No moisture was found. Insolubles were at limits showing that oil was exposed to excessive heat and use. Silicon was high but the Virgin ATF had quite a bit at 13ppm. The TAN read 0.8 in this sample so the oil didn't become anymore acidic. With the miles put on this oil the viscosity was lowered and reads normally. Universal averages are based on an oil run of ~26K miles."

First Column is the element or property
Second column is the 50K mile reading
Third column is Blackstone's universal average based on ~26K mile run
Fourth column is the virgin oil sample reading
Sorry about the formatting.

E/P 50K Avg VOA
Al 8 14 3
Cr 2 0 0
Fe 195 54 7
Cu 24 23 0
Pb 27 3 0
Sn 0 1 0
Mo 3 1 0
Ni 1 0 0
Mn 3 1 1
Ag 0 0 0
Ti 0 0 0
K 1 1 1
B 11 211 18
Si 27 11 13
Na 5 4 3
Ca 457 363 67
Mg 4581 155 5032
P 3177 96 3056
Zn 1267 257 1135
Ba 4 2 0
SuS Visc 44.5 43-51 56.6
Flash 305 >335 365
H20 0.0 <0.1 0.0
Insol 0.1 <0.1 0.0

 

Here is a clean up of the table.
Let us know when you get them to update their comments for an MT.
If I understand correctly the Avg numbers are questionable so only compare the VOA and 50K. Right ?

 

You guys r some anal B*star*s how much did you spend for this labt testing prolly more than the actualy fluid itself right. More power to you man, it's cause of people like you that people like us get more knowledgable.

 

Since I do my own maintenance, I don't mind spend $20 on an oil test. It eliminates the hyperbole and anecdotes and lets me see through the BS that the dealers, marketers and others keep spouting.

So what did I learn from the test? That the GM fluid was shot after 50K miles. I left it in too long based on how good the shifting felt. Next time I'll change it at 25K miles and see what the wear numbers look like. If they don't look significantly better I might change to Redline or Amsoil MTF.

 

The average wear numbers seem valid. I don't trust the add pack numbers.

Thanks for cleaning up the data, much more readable.

 

[QUOTE=Dr.P] how much did you spend for this labt testing prolly more than the actualy fluid itself right. [QUOTE]

At a cost of 20 bucks id say its CHEAP information as to whats going on with your car

 

how do i change transmission fluid...where do i drain it?

 

[QUOTE=fsttyms1][QUOTE=Dr.P] how much did you spend for this labt testing prolly more than the actualy fluid itself right. Shoot that's not bad. I'd figured it'd be $50-$100 easy, cool deal