Castrol BOT 303/350 vs Honda MTF

[Wampahoofus]

I'll be changing out the MTF in a 2012 Honda CR-Z soon, which specs Honda MTF. My understanding is that this is an ATF-like fluid with an MTF-like add pack, per MolaKule. I take this to mean that it is like a modified Honda DW-1 ATF.

Since BOT 350 (in the guise of Mopar C-Series Manual Transmission Lubricant 75W GL-4) has a similar viscosity it seems like it would play nice with the Honda trans. The add pack seems very similar to the Honda fluid as well, if this is any indication. Compared to the UOA/VOA seen here for Honda MTF, the Castrol seems to be a bit more shear stable too.

Would using the Castrol gain me anything? The relative shear stability, GL-4 designation, and the fact that it is 'designed from the ground up' as a purpose-built manual trans oil are all pluses. I have no problem using the Honda fluid, but what would life on BITOG be without putting different fluids in applications they're not expicitly designed for?

 

[sciphi]

Castrol BOT 303? Run away screaming! I had that junk in my Cruze's manual transmission. Notchy when cold, and had a high-RPM grind into 2nd. This was on a transmission with a few thousand miles on it. After putting up with it for the first 18k miles I had the car, it got happily ditched in favor of Amsoil Synchromesh. The grind went away and cold shifting improved noticeably. 78k miles later, the transmission still shifts better than new with the Castrol in it!

http://www.amsoil.com/shop/by-product/tr.../?code=MTFQT-EA

 

[OneEyeJack]

I'd consider Red Line MTL. I use it in my Honda Civic listed below and it's great stuff.

 

[Mr Nice]

Amsoil MTF or Honda MTF would be my choices.

 

[Greasymechtech]

Wasn't the Cruse originally filled with BOT 0402 which was too thick for weak wristed US consumers?
BOT303 is the new fill and replacement.

cst 40/100c
BOT 303 31/6.2
BOT 350 30.5/6.3
BOT 338 36.8/7.3
BOT 0402 75.6/13.1

Pentosin MTF2 38.3/7.7
Ravenol MTF2 39.6/7.8

Hondas MTF started at almost 11cst as a replacement to the 10w30 motor oil fill of years past. Current Honda MTF is ~7.5cst.

Go thin BOT for max mpg. But 338 might be closest to what Honda now specs.

 

[Sunnyinhollister]

Originally Posted By: sciphi
Castrol BOT 303? Run away screaming! I had that junk in my Cruze's manual transmission. Notchy when cold, and had a high-RPM grind into 2nd. This was on a transmission with a few thousand miles on it. After putting up with it for the first 18k miles I had the car, it got happily ditched in favor of Amsoil Synchromesh. The grind went away and cold shifting improved noticeably. 78k miles later, the transmission still shifts better than new with the Castrol in it!

http://www.amsoil.com/shop/by-product/tr.../?code=MTFQT-EA



When I changed out the 303 in my Cruze for the thicker Amsoil MTF, the only thing I noticed was the transmission seemed quieter. The 1 to 2 grind is still there if I shift quickly. The UOA of the 303 did not show any shearing for the 10k it was in there - nor should it. I think the [censored] shifting is just due to the design of the M32 tranny. I'll be changing to Amsoil Synchromesh at 20K and sending a sample out of the existing Amsoil 75W-90 at that point. I'll report back then.

Here's the link to the last UOA:
http://www.bobistheoilguy.com/forums/ubb..._30#Post3418299

Cheers!

 

[sciphi]

Not sure
Originally Posted By: Greasymechtech
Wasn't the Cruse originally filled with BOT 0402 which was too thick for weak wristed US consumers?
BOT303 is the new fill and replacement.

cst 40/100c
BOT 303 31/6.2
BOT 350 30.5/6.3
BOT 338 36.8/7.3
BOT 0402 75.6/13.1

Pentosin MTF2 38.3/7.7
Ravenol MTF2 39.6/7.8

Hondas MTF started at almost 11cst as a replacement to the 10w30 motor oil fill of years past. Current Honda MTF is ~7.5cst.

Go thin BOT for max mpg. But 338 might be closest to what Honda now specs.



Not sure, I think it was more for fleet fuel economy. The 303 is noticeably thinner than the 402. That would affect EPA MPG numbers since those tests are conducted with a cold engine/transmission. Less viscous = less fuel consumed overcoming parasitic drag = better EPA MPG rating.

Anyhow, I still think the 303 is bottled rubbish. If the OP loves the stuff, I'll amend my opinion to "bottled rubbish for a GM M32 transmission"!

 

[Wampahoofus]

I have no significant opinion on the stuff - seems to work well in Fiat gearboxes. I just have it readily available at the garage I work for and thought I might gain something from a GL4 oil. After making inquiries on price, I think its already decided.