Synthetic oil dilemma

[Rollifahrer]

I pulled the cylinders and need new rings...problem is I still have synth oil in the crankcase. (Thought it was just the heads that needed work.)

After I warm up the pan and drain the oil, should I refill it and crank the starter to purge the synth from the lube system? If I need to do that, should I drain the new oil? Should I use a lighter oil for this process?

Is any of that really necessary to break in the rings on dino oil, or will the synth dillute enough in the new dino oil?

(I think these are generic questions, but it's an R65 w 57K.)


Thanks,

[osbornk]

I don't think you need to do any more than just change the oil. the oils are compatable and there is not enough synthetic to make a difference.

[lkchris]

Keep using synthetic oil.

[ccolwell]

If you want to err on the safe side and not through away the expensive stuff, drain the synthetic into a clean container, run it with dino for a thousand miles or so, and then reinstall the synthetic.

[osbornk]

Keep using synthetic oil.

YOu need to use dijno oil so the rings will seat. The rings have to wear enough to conform to the cylinder. A thjousand miles is not nearly enough to seat the rings. I would use dino oil for at least 10,000 miles. My airhead and my K bike leaked around the seals and seals with synthetic but quit when I changed to dino oil. The airhead quit leaking 10 years ago and continues to be dry.

[aaaaaa]

Yep, You need the dino oil for breakin absolutely. No major manufacturer uses synthetic right from the factory. right. Except BMW, Chevrolet, Harley Davidson, Honda, Porsche, Audi, Lexus, Nissan, Mercedes Benz, Can I stop now.
robert

[ccolwell]

Yep, You need the dino oil for breakin absolutely. No major manufacturer uses synthetic right from the factory. right. Except BMW, Chevrolet, Harley Davidson, Honda, Porsche, Audi, Lexus, Nissan, Mercedes Benz, Can I stop now.
robert

These are for newer vehicles built with much closer tolerances and modern metallurgy. It is not unreasonable to err on the safe side with older bikes. Dino won't hurt and might help. That said, I don't think thousands of miles are necessary even for older rings to seat. Hundreds, maybe.

[Rollifahrer]

Thanks for the comments.

Here is another issue: When I pulled the heads, the left piston was soaked w oil and there was a fair amount in the combustion chamber, and when I pulled the cylinder there was a lot on the piston skirt, and in the bottom end of the cylinder. Not so on right side.

My guess is that too much synth oil got into the cylinder, for whatever reason (Over fill before moving dipstick mark down? Leaving on sidestand for long periods? Both?), and didn't burn off because it is less combustible than dino and just built up.

There was also a very stubborn carbon build up on the bottom edge of piston that would not budge with SEAFOAM or other carbon busting chems. Again I'm guessing the synth oil combined with existing carbon to create that condition. (In addition to running lean and hot!)

One last tidbit: I rode it to Gillette from Ohio (4700 miles) and the oil level never dropped below the bottom mark.

It's water over the dam, now (heads redone and new rings), but I'm still wondering why there was so much oil on top of the piston.

[Isamemon]

was it on the side stand for a while before you pulled it down, if so, oil will seep by, even new rings. even with a few miles, an airhead has been known to smoke a bit if left on the side stand for a day or less.
If everything was within specs and you honed and put new rings in, I dont see wher the issue would come in.
Make sure you have the new rings correctly spaced, and there is a recomended order of the spacing
Oak makes reference to it in his top end overhaul manual

and yes, dont run synthetic during break in

as far as reusing the synthetic later, well, thats your call, I dont like reusing oils, especially when we are talking about 1 quart.especially if it sat in there while doing an overhaul.
If you want to reuse it , put it in your lawnmower, or in a car that uses many quarts, that it can mix with

[Rollifahrer]

I found the oil when I initially pulled it apart; it's back together and after 200 easy miles seems OK. Bore measured in spec; end gap of new rings in spec., so far no oil loss, so I think problem is solved. It's just that I'm not sure what the real problem was.

I was wondering more than anything whether there was so much oil on the piston crown because it wasn't burning off as is typical of dino oil in airheads. I never saw smoke, ever, from either pipe with the synth oil. It might not matter, but I can't see wet oil in the combustion chamber being a good thing. I'm thinking if synth doesn't burn off, I might be better staying w dino oil.

Any thoughts on using moly with 20w50 instead of synthetic (after break in)? I used a moly laced gear lube in my oiler gear box and it cured a shifting issue. I plan to use a moly additive in the synth next oil change on the oiler. (I hope opinions on additives aren't as contentious as those on oil in general! But if anyone has had a bad first hand experience with moly, I'd like to hear about it.)

[Polarbear]

They will run on just about any oil you put in there! BUT, obvious choices are the smart thing here. Synthetics? You don't need'em, but its only money and the new engine should NOT have it for thousands of miles. BMW uses synthetics from NEW? Who said that? Not in any I've seen. Some folks may, but they can do what they like, they bought it. Its just not recommended by BMW. The low mark on the dipstick is ONE quart of oil still in there, which is SO little. The engine only holds 2 to start with:). Better keep it nearer the full mark. The first sentence is so true, as the engine was overengineered and is so very tough. We can't seem to kill them easily:). Reg Pridmore told me personally, years and years ago, Randy and John, "I cannot kill these running them full speed,WFO, for hours and hours on the track, so what makes you think you can, riding the streets?". GOOD POINT! Ride 'em harder, they are built for it and the rings will seat. John, my best friend I rode with 30 years, was a friend of Reg and was a BMW rider for 50+ years. A friend missed:). Randy"Polarbear":thumb :usa

[Rollifahrer]

Polarbear,

Thanks for the wisdom.

I didn't know the difference between marks was a full quart...won't do THAT again!

Yes, I agree airheads, and German vehicles in general, are made to run hard. The biggest probem with VW boxer engines was shifting early and lugging the engine. Electronic engine management has elinimated most of the woes of not running hard enough. Germans tend to be rev-junkies. WhenI lived in Hamburg traffic lights operated like dragstrip Chrstmas trees: the red light would stay on,the amber light would flash, then green. All the while every car in line started to rev when the amber flashed, and started slipping the clutch just before the green, then wound out 1st gear, and sometimes second. Woe to the poor (usually American) fool who waited for green to "get it in gear". Through town my friends would leave it in 2nd or 3rd and run to the redline and back down to adjust to traffic flow. Due to the high price of gas, even 20 years ago, and the displacement tax (Hubraumsteuer) they pay every year, Germans have been motivated to design small cars that are fun to drive and run reliably for many years. 1.1 L turbos get the job done in city driving and are remarkably competent on short Autobahn runs, then you have diesels available in nearly every model, including "sporty" 3 and 5 Series coupes....well got off topic, but it is surpising how much they get out of small engines by not being afraid of high revs.

[widebmw]

I don't know about a R65 but on my R100R after I drain the oil I put 2 quarts in and it show just a little at the bottom of the dip stick, below the lowest mark.
Then I put in 1/2 quart and that brings it up to full on tha dip stick.
It would be best to add your oil a little at a time and check the the dip stick.

[Rollifahrer]

Someone told me the dipsticks were mismarked, and the top mark was too high and could cause overfilling. Next oil change I carefully measured 2.4 quarts, ran the engine, then remarked the dipstick with a file to match the actually level with the specified amount. I'm not sure which models/years were affected, but too much oil in airheads is not good, especially if you use the side stand a lot.

I think next oil change I'll add 1 quart to see where it hits the dip stick, then 1/2 quart to make a new low mark.