Cruisin' through Wally World yesterday waiting on the Ma-inLaw's new tires and didn't see any Mobil 1 15w-50 red cap. They did have some new Mobil 1 15w-50 Extende Performance. Hmm, time to do a little research.

 

Never heard of it, post back with whatcha learn.

Mac

 

Don't want to start a long debate but , DO NOT USE ANY OIL THAT IS NOT DESIGNED FOR MOTORCYCLES. Air cooled motors require different additive packages.

 

240 Deuce is RIGHT....... Different Heat range, tolerances....metalurgy!

Bruce

 

That debate was settled a long time ago. I've used automotive oils in every HD I've owned. One of 'em, a '78 FLH, went 125k miles before it needed a top end, and over 200k miles before it needed a bottom end. Used Castrol GTX 20w-50 over most of its life. My '87 FLST has over 100k miles. I use Mobil 1 15w-50 red cap (car oil) in it.

After seeing the test results on many different oils, the big thing that stood out was most so-called motorcycle oils were no better, and often inferior, to the better auto oils. And even the best mc oils were only marginally better than the same-brand auto oil, Mobil 1 being the one example I'm most familiar with.

Why would I want to use an inferior mc oil at a jacked up price instead of a superior auto oil at 2/3 to 1/2 the price? And since even the best mc oils are only marginally better than the best car oils but cost twice as much, I'll stick with the car oil.

Do the research. It's an eye-opener into the world of salesmanship, and makes you understand why it's good practice to doubt any manufacturer's claims.

Not trying to come on too strong here, just wanting y'all to question everything! And especially question HD!

 

So far the only stuff I've found on it were analyses on the 5w-30, and 10w-30 grades. These should have additive packages quite a bit different from the 15w-50 as they have to meet different specs. One of the big differences between the old & new is the much greater amount of calcium, used to control acidity. That will probably be similar in all the grades. The 15w-50 doesn't have to comply with the lowered phosphorus (anti-wear additive) limits imposed on the lower viscosity grades. But I believe the 15w-50 even now has friction modifiers that may make it undesirable in the primary with a wet clutch.

 

Skip,

I well remember the debate...I know where you are with it, my question is this...what have you found in your research with regard to the wet clutch, car oil beingg too slippery compared to the car oil. I have searched the web and read a few articles about it, and the one thing that seems to stick out is the wet clutch...thoughts?

Mac

 

I just touched on it right before you posted. Was getting ready to add a bit more.

The friction modifiers that are in the car oils can be detrimental to a wet clutch, causing it to slip. But it doesn't always happen, and seems to happen less in the HDs than in some of the metric bikes. I'm running the Mobil 1 15w-50 in my primary, and it has the friction modifiers. I've had no problems with clutch slippage. But that doesn't mean someone else won't. Caveat Emptor, and I wouldn't feel right about recommending it to anyone. It's just that my experience is good. FWIW, I'll probably be pulling my clutch plates out, cleaning them, and then go back to using my old primary standby- ATF.

As far as using the auto type in the tranny, I wouldn't. I know some who are, and have had no problems. But I know the mc version of the same oils has been modified to withstand the greater shear stress encountered in a tranny. That is one of my concerns with using the auto oil in the tranny. The other concern is the several bike mechs who've posted of suddenly running into a lotta HD trannies crapping out when the owner switched to engine oil, be it car or mc type. I'll stick with the Castrol or Mobil 1 synthetic gear oil in the tranny.

 

Skip,

You got me further into where I was before...I'm going to stick with the MC stuff, fully synthetic (at least as much synthetic as Mobile 1) will give me, I know it ain't TOTALLY synthetic. The few extra dollars is for peace o' mind I guess.

I'm still curious 'bout the other stuff for my 'vette though.

Mac

 

That debate will never end. As I have said before, OIL IS CHEAP, MOTORS ARE NOT. Most oil company info is hyped bullshit. I run only Mobile 1 MOTORCYCLE OIL in my bike motors and they show NO WEAR even though they make twice as much power as a stock motor. You do what you do and I will always do what I do.