I heard mention on another forum that using car oils in motorbike engines is bad for the clutch... IF they have friction modifiers in them.

I bought 5L of Mobil 10w40 semi-synthetic oil... will this affect the clutch?


Cheers,
Andrew

I have Mobil 1 in my bike at the moment. This page explains how much it matters enough to satisfy me.

http://motorcycleinfo.calsci.com/Oils1.html

I haven't noticed any problems.

James

Quote from: Beelzeboss on January 20, 2009, 02:13:21 AM
I heard mention on another forum that using car oils in motorbike engines is bad for the clutch... IF they have friction modifiers in them.

I bought 5L of Mobil 10w40 semi-synthetic oil... will this affect the clutch?


Cheers,
Andrew

no, it will not make the clutch slip. buy ANY BRAND you like and you'll be fine. motorcycle specific means you pay more, for nothing. the friction modifiers are the ONE AND ONLY thing to stay away from.

by the way, it says on the dipstick 10w40. feel free to modify that for you weather conditions.

i used castrol 10w40 CAR oil for over 20,000 miles and only had one occasion that the clutch slipped. this was after buying a quart to top off on a group ride, which contained the modifiers.

if you happen to get a quart or complete oil change that uses FRICTION MODIFIERS, all it takes is a proper oil change with the proper oil to flush out the problem. no smoke n mirrors, no $1000 'engine flush'ing, nothing like that.

2 dumb questions:

What are these friction modifiers?

And

How do you know if the oil has them or not?

Thanks,

Nick

For the most part, the modifier is a heavy dose of "moly" or molydibedum sulfide or some such spelling.  It is a great high pressure lube and gear oil is loaded with it.  PTFE or teflon may be another, like Slick 50 snake oil.  Heavy equipment rated motor oils are typically formulated with wet brakes and wet clutch packs in mind and can be excellent choices for us.

prs

Quote from: utgunslinger13 on January 20, 2009, 06:35:36 AM
How do you know if the oil has them or not?

The API service seal will state "Energy Conserving" if the oil has friction modifiers that will slip a wet clutch.

Thanks guys! 

also if it less than 10W.... IE 5W....    it probably is bado bado

Thanks very much guys. I did check on the bottle before buying to see if it had friction modifiers, and I didn't see anything. I assumed IF they had friction modifiers they would want to advertise that to entice people to buy it.

Andrew

Quote from: werase643 on January 20, 2009, 12:30:42 PM
also if it less than 10W.... IE 5W....    it probably is bado bado

Nothing wrong with 5w, especially when the weather turns cold for the winter. The first number is the thickness when the oil is cold. You put  put the most wear on the engine when you first start it (or so I have heard) so I figure a thinner oil when its cold can only help with better warm-up times and less engine wear. The only reason you wouldn't want to use 5W is if you start to get clutch slippage because the oil is too thin.

btw, its very possible I have no idea what I'm talking about.

I used Rotella synthetic 5w-40 with no problems at all. The clutch won't slip unless there are friction modifiers in the oil. The only problem with running 5w is you may experience increased oil consumption as a 5w-40 oil is a 5w base oil with more viscosity index improvers to keep the 5w from excessively thinning out under high temps. Regardless there is still 5w oil so oil that thin will get past seals and rings. On my GS500f I'd notice it go from the top of the hash marks to the bottom on the dipstick in only 1500-2000 miles. When I use the Rotella 15w-40, oil  consumption would be only about half the hash marks at 3000 miles.

I use the exact same oil with similar results, it does burn a lot. I'm glad it's the oil I'm using and not the bike.