Gear Oil for CR125

[Sam Zavaglia]

Just to start another comedy of information on these forums, I use Castrol MTX which is very cost effective in Australia. Not sure if this is available in the USA.
http://www.castrolmoto.com/au/our_oils_new/mtx_gear_oil.php
I only change my gear oil at least 1-2 years apart.

Anyway, I put Castrol MTX into my very first CR125 kart engine. Over six months later, the Redline rep said...."mate you gotta try this blah blah blah....and more horsepower.

So since there is a drop in HP through the gearbox and I got the stuff for free for testing and feedback, thought I'd test it proper. I went to a "rolling road" dynojet dyno with my gearbox still with original Castrol MTX and got a read out. Drained the gear oil while still warm and dropped this exact Redline stuff in.
http://www.redlineoil.com/product.aspx?pid=112&pcid=26
The next dyno read out was exactly the same .......could not spot a single difference......what a load of crap I said to myself.

This Redline stuff now stayed in the engine for a further 2 years....never changed. So after the engine was 3000miles and nearly 3 years old, I've had Castrol MTX for over six months (at least 6 race meetings) and then 2 years without a change on the Redline stuff, I decided time to change the crankshaft as preventative maintenance.

After opening the crankcases, the gears/dogs all looked virtually perfect, the shift forks like brand new.
I also did another engine rebuild with over 2 years on Castrol MTX never changed, very similar results, maybe not quite as perfect as Redline but still very remarkable and worthwhile staying with Castrol MTX.

Both engines, no magnetic drain plug, no notable bits of metal in the gear oil.

This is the engine with over 2 years on a single fill of Redline, over 2000miles on that gear oil, I know you can't see the dogs but imagine it looks as good as the rest of it.



Has everyone else got the same results? I imagine so since I do not read any bitchin about CR125 gearboxs on here.

Has anyone got notable differences between different brands of gear oil that are specific to motorcycle/wet clutch use?
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www.samzavaglia.com

[Jeff DeMello]

I only used Mobil 1 synthetic oil with no gear box problems. I would change after every season of racing..
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Jeff DeMello
Emmick F125 Pavesi

[Ken Schilling]

Wow, you guys change your transmission oil very infrequently compared to me... I change mine every race and use TransOil 2T 10W30. The CR-125 trannys are considered to be bulletproof and I do it this frequently as a relatively inexpensive preventative measure as well as trying to extend the life as much as possible. I'm on a shoestring racing budget and don't want to open the bottom end unless absolutely necessary.

http://www.corseracing.com/Motul-TransOil-Petroleum-Gear-Oil-1L-One-Liter-Bottle-10W30-p3568.html?gclid=CMX42YLY8LQCFayPPAodq2QATA
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Ken Schilling
#21x / S4 / ProKart Challenge (PKC)
SKUSA Data Administrator

Good luck is where preparation and opportunity meet!!!

The opinions I express are mine alone and do not reflect those of any organization of which I am a member.

[Mike Goebel]

Sam you have to change it more offten It "Will" never last as long as it already did!


Mike G.
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Closet KZ Lover!!!
mfg Technology Centre
So Cal’s #1 Non Profit Engine Builder

[Sam Zavaglia]

[Jim McMahon]

Do you still have the oil Sam? You should send it off for analysis.
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[marc-andre hubert]

i use honda racing oil 75w90 shift great and offers great protection

[Sam Zavaglia]

[Jim McMahon]

[Michael Taksa]

The consensus is that the tranny on that motor is bulletproof, so it will run on whatever you put in it. I use mobil1 syntetic 5W30, used 10W30 in the past, but now my car wants 5W30, so my kart gets the same oil I already have.