Does it matter if use 2- or 4-stroke trans oil

8 replies to this topic
  • gottaroost

Posted November 10, 2004 - 05:16 AM


I have several Silkolene Comp4 Semi-synthetic 10W-40 quarts for 02YZ426 and hate to have it just eyeballing me while I have no opportunity to get to a mx shop before tomorrow.

I have always used Silkolene Medium Gear Oil SAE 85/90 in my 96 KX250...I am sure this is a novice question...but what difference would it make if I used a quart of 4-stroke lube in the KX?

I do not want to mess anything up but it just seems like having something in the tranny would beat the spooge in there now.

Tried to search this one but did not find anything that addresses my crossover concern.

Also, is there anything over the counter I can nab at an automotive parts house for a 2-stroke?

  • Butta

Posted November 10, 2004 - 05:37 AM


Well, from my perspective, you're looking at gear lube versus motor oil. The wieghts are the first thing that throws off any inkling to say that it's going to be ok. I would say consult your owner's manual and use an oil that meets those specifications....I think you'll find that, unfortunately, the oil you have is not recommended. Don't mess with it....spend the extra time/$ and get the right lube, your bike will love you for it!!

  • sirthumpalot

Posted November 10, 2004 - 06:30 AM


Open the manual for the KX250 and take a look. Use the oil that is recommended in there. Many of the older bikes were OK with 4-stroke oil in the gearbox, but I haven't had a need to check any of them lately. Regardless of what you read on the internet, read the manual and follow what's recommended there and you can't go wrong.

  • Yamaha35

Posted November 10, 2004 - 12:25 PM


I purchased some gear oil 85w from the local Auto store for $2.39. Worked great last 2 rides. Way cheaper than MX store and you get bigger bottle.

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  • rides426

Posted November 10, 2004 - 12:38 PM


Automatic transmission fluid is a good short term fix with going out to buy anything.

  • saucebox

Posted November 10, 2004 - 02:58 PM


i'm pretty sure my 1990 kx 125 and my friends 2000 kx 250 both recomends 10w30 or 10w40 oil. and i'm almost betting thats what your owners manual will recomend.. and if it works with your thumper it'll work on your 2 smoke.. the biggest deal is using an oil that wont cause your clutch to slip. the 80w seems like it'd be pretty thick to me??? probably see a power increase runnin the 10w30 or 10w40 in it

  • ripntear

Posted November 11, 2004 - 05:47 PM


Check out this Viscosity conversion chart.
As you can see the 80w SAE is toward the upper end of 20w engine oil. If your manual calls for 80w SAE gear oil I wouldn't use anything less than 20w50 SAE engine oil unless you get into a good synthetic.

ripntear :cry:

  • grayracer513

Posted November 11, 2004 - 08:15 PM


Besides the different viscosity scale, the 2 biggest differnces between motor oil and gear oil are that gear oil resists shear better, and gear oil is usually non-detergent, so that it will not carry debris in suspense, but let it settle out to the bottom of the trans.

Motor oil needs this ability to transport debris to the oil filter. It isn't ideal, but since all YZF'rs use motor oil in their transmissions, it obviously works. Your clutcg will have to like it, though.

  • 226DAD

Posted November 16, 2004 - 12:52 PM


Silkolene Comp4 Semi-synthetic 10W-40 is good quality oil and is what we always ran in our 02 125SX and 02 250SX. Both went over 1 year on the original clutch, gear action was always very smooth.

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