twin cam oil weight question

[1100s nut]

I have a question, my owners manual says the twin cam should use 10w40 or 10w50. I have allways used 20w50....any cam head guys use 20w50?

TIA,
Lane

[1%er]

I split the difference at Wally World and got M1 15w50. Engine is still in one piece. Used it on oil/hex heads too. And my Harleys.

[1100s nut]

Well I do the same, but the book says diferent so just wonder others feel about it.

[1%er]

I guess it would be a factor if I lived in a cold climate; but, that's not the case. I spend most of my time worring if the 50 weight is enough.

[tm1100s]

Do a google search for 'mobil 1 10w-40 15w-50 pds' . There's one product data sheet with both oils on the same page for comparison. Look at the high and lower temperature viscosities and you'll see that the low temp viscosity is quite a bit different while the high temp viscosity only has a few points difference. While I have my own take on this, opinions vary, especially here.

I've attached an analysis of un-used Mobil 1 15W-50 just for entertainment purposes.

[1100s nut]

Thanks TM. I just bought as 2013gs cam-head so I want to do the right thing and also cover my butt. The owners manual is more complex than it needs to be. I think 20-conventional oil will be fine for break in. I would probably worry more if they called for a 10w60 like in the M cars.

Lane

[Bob Hancock]

Lane I use 20w-50 full synth for everything. Makes it easier when you have multiple bikes and it hasn't been a problem.

[1%er]

The new question that pops into my head is, now that BMW is going water/air cooled and using a wet clutch, will the Wally World M1 auto synthetic oil be appropriate? This is a bit of thread drift; but, your question seems to have benn answered, Lane.

[ckcarr]

Did you buy a Harley?
Mobil 1 20w50 for the real "Twin Cam."

[tm1100s]

Originally Posted by 1100s nut

Thanks TM. I just bought as 2013gs cam-head so I want to do the right thing and also cover my butt. The owners manual is more complex than it needs to be. I think 20-conventional oil will be fine for break in. I would probably worry more if they called for a 10w60 like in the M cars.

Lane

My opinion is that they're less concerned with the protection at operating temperature and more concerned with engine wear during initial startup and warmup, the main reason for the 10W oil. For this reason, the use of the heavier weight oil for break in purposes appears to defeat the manufacturers purpose. Will you really get better startup/warmup oil protection from the 20W during break-in? I'm not sure that reasoning is valid. They also carefully chose oil that is a minimum 10W-40 weight. As it happens, oil lighter than 10W-40 is gradually having the zinc/phosphorus antiwear additives drastically cut back for various reasons, mostly environmental, while 10W-40 and heavier oils retains the high anti-wear additive levels. This is a general observation and may vary but I have a couple more oil analyses to show this trend that I've done for my own reasons. Flat tappet owners be aware.

But, we have a good opportunity here. If you use the 20W, and we can get someone else with the same engine to use the 10W then change the oil at the same break-in interval, take samples and have both tested, we can have some top notch data to use later. Break in oil samples usually have higher levels of metals from the break in process. The difference will give us the whole story. Blackstone Labs- $25/sample.

[1%er]

Originally Posted by ckcarr

Did you buy a Harley?
Mobil 1 20w50 for the real "Twin Cam."

You talkin' ta me?

[1100s nut]

Craig, no, I bought a GS that is a twin cam. It is basically like the HP2S engine but detuned and probably less exotic internals. I am going to us 10w40 as per the manual and at 6000 miles switch to the recommended 10w50 synthetic.

Thanks for the input guys,
Lane

[ckcarr]

Originally Posted by 1%er

You talkin' ta me?

You already got one watermelon head!

[lkchris]

Originally Posted by tm1100s

My opinion is that they're less concerned with the protection at operating temperature and more concerned with engine wear during initial startup and warmup, the main reason for the 10W oil.

I think in 2013 the motivation for 10W is the fuel economy numbers.

[tm1100s]

Originally Posted by lkchris

I think in 2013 the motivation for 10W is the fuel economy numbers.

I'm sure that helps, especially as the minimum weight that BMW is willing to use. Anything lower in a 0W or 5W that has the 'Energy Conservation' label and you lose a good portion of the anti-wear additives. Of course, this doesn't preclude BMW from coming up with their own oil spec like they and others are already doing with the autos.

Someone in here has worked for an oil company and was involved with this. Who was that? I'd like to get the inside information.

[1100s nut]

I went with 10w40 like the book calls for, and I talked with my parts and he said the that's what they use in the twin cam bikes. When I get to the 6k mark I will go to the spec. 10w50 syn. I am doing this more for CYA than anything else as I am sure 20w50 is fine.
Lane

[1100s nut]

I will say the the gas mileage is better than any bike I have ever owned. I am running fairly hard, brisk take offs and I am getting 48-49 mpg indicated by the computer. It will be interesting to see what I will get once engine break in is complete and riding conservative.

[1%er]

Lane, as you know, gas mileage on these bikes is altitude dependent. The HP2 Sport came frome the factory with full syn oil in the crankcase. burnishing in the branes is probably more critical than anything you'll do with the engine. Have a nice day.