mixed viscosity oil with straight weight oil for the engine??? I've been running Mobile One Synthetic 20-50 in my bike and I haven't checked the level in a while (I know! ) b/c she doesn't leak a drop! That being said, I was 2.75+ quarts low today! I could only get my hands on some straight 50W (non synthetic) today b/c the nearest town is 30 miles away. Is there any problem mixing straight weight oil with mixed viscosity oil??? I've always heard you can mix synthetic with non-synthetic but an old timer is telling me I shouldn't mix the two different types.

Evidently this thing is burning the oil up. I ride hard but I have NO idea where 2.75 quarts of oil went...like I said, she doesn't leak! The darn transmission oil (Mobile One Synthetic 75-140) smelled burnt too. I know I ride hard but daggone...I'm just now hitting 3000 miles since my last oil change.

My bike hasn't been sounding right the last few times out and the last ride I could not get her over 100 mph. I'm afraid I've probably done some serious damage. Just hope she doesn't blow and lock up on me. I can't afford a tear down right now to check things out. Damnit!

I appreciate ya'll's thoughts!

 

Open your primary.
The missing oil could be there.

Sounds like a rebuild is in the immediate future.

 

Oh yeah as to mixing the oil since you are already 2.75 quarts low I would just go ahead and do an oil change.

 

I've mixed different weight dino oil before with no worries. Mixing syn and dino, I don't know about that. 2 1/2 quarts low is the big problem. Guess we'll be seeing your build thread.

 

Yeah...but I have to ride in the mean time. I don't like the sound of having to do a rebuild any time soon. If the darn thing seizes up at 100, it's likely to spoil my day!

 

Put a catch pan under the derby cover and pull it off... you'll now real quick whether or not you're burning oil or if your crank seal went out. Honestly, if you're burning that much oil, your plugs should be fouled... what do they look like? If the plugs don't look ****ed, check your primary next to see if the crank seal **** the bed. My money is on the crank seal... she'd be smoking like a **** if she was burning that much oil.

 

That oil consumption is consistent with what I got on Hyacinth during our visit to the USA/Canada way back, although temps were very high for much of that trip. In 3,500 miles we used around 3 quarts IIRC, although I was checking regularly! I would have no qualms mixing synth with dino oils, they are mostly made to meet the same specs. It would be a waste to put fresh oil in and then do a change soon after, but if that's what you have to do......

 

Is the bike your only mode of transportation?
I don't think anyone likes the sound of having to do a rebuild at the beginning of Sumner.
If it sizes up it is likely to spoil more than just your day.

Best thing to do is find out what is wrong and fix it.

 

It will be cheaper to fix it now instead of waiting for catastrophic failure later.

 

Let's wait until OP pulls his derby cover off before we write his engine off, although I'd rather pull a top end off than take the primary off.