Flushing out car oil in a motorcycle?

[nthach]

I was at the local AZ a few nights ago getting car wash soap(I know but I wasn’t waiting for Amazon or felt like going on a Costco run) and someone grabbed two bottles of Valvoline motorcycle oil and Gunk Engine Flush after telling the counter man he filled his Yamaha bike with “car” oil. I told him he didn’t need to run that vile engine flush, all he needs to do is drain the car oil out and fill back up with the motorcycle oil. He said he barely got his bike off the freeway, the clutch wasn’t engaging.

My question is, did my advice help him avoid further damage to his bike by skipping the flush chemical and going straight for the “right” oil? How much damage did he do with the “car” oil on his wet clutch?

 

[CharBaby]

My belief is that the oil in the motorcycle may only need to be changed out and not flushed however, others will chime in with their experiences/opinions. I mean, maybe 2 drain & refills with the correct oil may be all that is needed to get all of the correct oil in the engine/tranny for a wet clutch system.

 

[Chris142]

I have been riding since tre 70's and never had a clutch slip on any oil car,diesel or bike

 

[CourierDriver]

WE men go brain dead sometimes,,,,run what the mfgr says to run,,,My Harley, ancient of days, 1996 , engine oil 20w50 and the same oil goes into the transmission, yes I use motorycyle oil...........................just change it once a year............, average road trips on weekend is only about 150 miles round trip,,,thats about it for me...

 

[BusyLittleShop]

It is likely given the numbers that our motorcycle oil is chiefly
reformulated Auto oil... the degree of change reflects market share...
either way Auto or MC oil will meet and exceed your mileage
expectations... so a flush is not recommended...

Example:
Here are virgin oil samples of $4.89 a quart Mobil 1 Auto Oil 10W40
and $9.98 a quart Mobil 4T Motorcycle specific oil... listed in parts
per million are minor differences in the additive package you're
paying for...

 

[BusyLittleShop]

oil? How much damage did he do with the “car” oil on his wet clutch?

No damage... we observe that the primary cause clutch slip
are high mileage... mileage is the constant among all of the clutches
that begin to slip... oil choice whether MC approved or Auto is not a
constant... High mileage is the constant where all clutches begin to
loose grip due to normal glazing and contaminates that build up over use...

If you wish high mileage clutch life then you have to invest is some
good old sweat equity...

Inspect the friction plates for glazing... make sure you have plenty
of material to work with... your shop manual states clutch thickness
in thousands of an inch or mm...

First removed the contaminants with Acetone... pick a hard surface to lay
over a 600 grit black dry emery paper... rotate the clutch plate in a
circle... you're just busting the glaze... don't get carried away
remove too much material... You should end up with a friction plate
looks dull like a new one as opposed to a shinny glazed one... recheck
thickness...

Next check the pressure plates for bluing caused by localized heat...
make sure they are not warped... consult the manual for a thickness
range... now removed the contaminants with Acetone and wire wheeled
them to erased the blue and also to generally scuff up the surface...
you should end up with a dull surface free of Blue marks...

 

[DGXR]

I would never use an engine flush in a shared engine/transmission with a wet clutch.
In this situation I would do as you said, drain the "car" oil real good and add motorcycle oil. Change filter too.

 

[HangFire]

No damage... we observe that the primary cause clutch slip
are high mileage... mileage is the constant among all of the clutches
that begin to slip... oil choice whether MC approved or Auto is not a
constant...

You keep saying that, but a trip to either of the Honda twins forums will show you that low mileage, high age clutches often slip.

I replaced my 40 year old Honda clutches a few months ago, at about 10,000 miles. Not high mileage, where many reports from the Dawn of the Internet had folks on this same bike going 50K and more on the original clutch. Steels were not blued. Steels were not warped. Reason? Age.

I've also read many a report of slippage immediately after changing oil to a car oil, you can call this age, but what do you call it when it stops when changed back to a 4T oil?

 

[Overfill]

You keep saying that, but a trip to either of the Honda twins forums will show you that low mileage, high age clutches often slip.

I replaced my 40 year old Honda clutches a few months ago, at about 10,000 miles. Not high mileage, where many reports from the Dawn of the Internet had folks on this same bike going 50K and more on the original clutch. Steels were not blued. Steels were not warped. Reason? Age.

I've also read many a report of slippage immediately after changing oil to a car oil, you can call this age, but what do you call it when it stops when changed back to a 4T oil?

good reasoning

 

[Merek]

I agree, maybe a flush or two with the correct oil is all that should be needed, I'd be leery of having anything else in the crankcase with a wet clutch. If they had a moto-guzzi or another bike with a dry clutch then it really shouldn't be a problem.

 

[ZeeOSix]

He said he barely got his bike off the freeway, the clutch wasn’t engaging.

Did he say what oil he was using. Sound pretty dramatic, so maybe it was some other issue going on. Unless he put some crazy oil and/or additive in his cycle.

 

[nthach]

Did he say what oil he was using. Sound pretty dramatic, so maybe it was some other issue going on. Unless he put some crazy oil and/or additive in his cycle.

From what he told me, Mobil 1.

 

[KrisZ]

You keep saying that, but a trip to either of the Honda twins forums will show you that low mileage, high age clutches often slip.

I replaced my 40 year old Honda clutches a few months ago, at about 10,000 miles. Not high mileage, where many reports from the Dawn of the Internet had folks on this same bike going 50K and more on the original clutch. Steels were not blued. Steels were not warped. Reason? Age.

I've also read many a report of slippage immediately after changing oil to a car oil, you can call this age, but what do you call it when it stops when changed back to a 4T oil?

That would be caused by the weak springs or glazed friction material on the plates. If you add oil that is energy conserving, it may exacerbate the weakness of the clutch, but be blamed as the cause.

Here is a spring from my 77 kz650. Left side is old, right side is new.

 

[twX]

I don't think a flush would be necessary at all, especially if using a JASO MA2 oil. The friction requirements of MA2 are quite a bit higher than MA1, and most motorcycles don't specifically require MA2. I wouldn't expect a small amount of of energy conserving oil mixed with MA2 to bring the oil below the friction requirements of MA1. If the clutch wasn't engaging at all, even at low to mid throttle, I doubt it was due to the oil unless the owner ignored all signs of clutch slippage at high throttle and damaged the clutch that way.

The oil in my motorcycle currently contains a mix of around 10% 5W-30 API SN energy-conserving oil, and 90% 15W-40 JASO MA-2. No issues to report. Clutch and gearbox feel are at least as good as with pure 15W-40.

 

[GSCJR]

I have never used MC oil in my bike, just off the shelf engine oil with the correct viscosity.

 

[Crash Bandicoot]

My experience is that most people here in the US take motorcycling way too casually and among not having any gear or working on their skills they also tend to have their bike in terrible mechanical condition so probably more worn clutch exacerbated by the wrong oil. Would just flush and fill with Rotella t6 and get a clutch kit ordered in in case that doesn’t fix it. Guy won’t listen to whatever you say. Have a neighbor like that. Helped him with a dead battery on his bike said “go get a battery tender they’re like 20 bucks” and check your battery (even leant him the tester) two weeks later asked me again for help and I told him I’m running late for a teams meeting.

 

[HangFire]

That would be caused by the weak springs or glazed friction material on the plates. If you add oil that is energy conserving, it may exacerbate the weakness of the clutch, but be blamed as the cause.

Here is a spring from my 77 kz650. Left side is old, right side is new.

Yes it could be, but not necessarily.

In my case, I swapped out to 25% Barnett's, burnished the steels and cork... I think 40 year old cork sitting in oil for decades of inactivity had something to do with it. I could see the oil level line across each steel and clutch plate. Others have reported the same when putting old clutches back into action, some of them basically brand new, but had been soaking all that time (at least the lower half had).

 

[FZ1]

I was at the local AZ a few nights ago getting car wash soap(I know but I wasn’t waiting for Amazon or felt like going on a Costco run) and someone grabbed two bottles of Valvoline motorcycle oil and Gunk Engine Flush after telling the counter man he filled his Yamaha bike with “car” oil. I told him he didn’t need to run that vile engine flush, all he needs to do is drain the car oil out and fill back up with the motorcycle oil. He said he barely got his bike off the freeway, the clutch wasn’t engaging.

My question is, did my advice help him avoid further damage to his bike by skipping the flush chemical and going straight for the “right” oil? How much damage did he do with the “car” oil on his wet clutch?

Yeah, you helped him. Too many friction modifiers in some auto oils for some bike clutches.

 

[Mackelroy]

as long as the clutch plates have not sustained any build up or slippage damage, just swapping to mc oil with a good clutch bite is .
enough.

My experience you cant trust all MA2 motorcycle rated oils either