Synthetic vs. Regular Motor Oil

[Big Daddy Norton]

Hello BMW community,
I tried looking in past posts for this subject but didn't see anything, so here's my situation. I am currently using high quality 20w50 mineral based motor oil in my 02' R1150R and it uses about 1.5 qts. between my 3000 miles changes. I was told by my shop technician that if I switched to a synthetic blend or full synthetic that the seal leaks that I currently have should stop.
He said that if the former owner of my bike was running a synthetic and then I started using mineral that could cause the seals in the engine to shrink and allow leakage.
What are your opinions, because I trust ya'll?

[Boxer]

Not sure what seals he is referring to but if seals were leaking it seems like you would be seeing oil weeping or dripping out somewhere. Now if the engine is indeed USING that much between changes, it is probably being burned in with the gasoline as it passes by the cylinder rings. I'm not sure I understand or buy the shop guy's reasoning. More likely it is just using (as in burning) that oil up because the original breakin procedures were done too gently and the rings never really seated well.
Ask him to do a compression test and see where it stands.
On the other hand, you could try using synthetic for a while and see what it does. I really doubt it will make a difference.

[towerworker]

How many miles on the bike? If it's under 25K it could very well not be broken in. In which case you do not want to go synthetic as it will just prolong the breaking in process.

When you refer to the oil getting past the "seals".....are you referring to the piston rings? Or is the oil leaking leaking out of the engine to where it's leaving spots under the bike.

+1 on the compression test as per Boxer. Me thinks that would be good information.

[riceburner]

Just for reference (concern?) my 97,000 mile rockster still uses about 1.5 litres between services (6,000 miles).

I've used mineral (Castrol Act-Evo 10W40) for the majority of the life of the bike. (I will admit that I've occasionally chucked in whatever was to hand when away from home and needing a top-up!)

[Big Daddy Norton]

Hey folks,

Thanks for the replies! Towerworker the bike a little over 32k on it now 10k of which I put on in the last year. I guess I should have been more specific with the "seal leakage", I have small leakages around the front of the engine (alternator belt area) and the base of the cylinders nearest the crankcase, none of which have ever left a puddle of oil on the ground. I believe a great deal of the oil loss is through the piston rings as Boxer had said. The tech was making suggestions and I was listening, but when things just don't sound right I like to consult ya'll.

Thanks for the advice on compression testing, I will have that done next.

Again, I do appreciate your opinions!

Walter

[CycleRob]

Slightly different compression test readings won't confirm or deny oil burning as it is the oil control ring's wipeing ability that determines oil burning. A low compression reading could indicate cylinder wall scoring damage and that will burn a lot of oil. A low compression reading also could just be burned/worn valve seats or valves, corrupting the cylinder wall integrity diagnosis. An individual cylinder leak-down test is the best diagnostic tool as it will specifically identify piston ring or intake/exhaust valve seat leakages . . . or any combination thereof. You would think that the bike's odometer reading would indicate whether the engine is broken in or not, but it also does not. Those two 101mm (4") pistons sweep a lot of cylinder wall surface area, twice/revolution. My previous bike, an `02 R1150R, did not stop using oil between the 6,000 mile changes until almost 18,000 miles. That was due to the way it was conservatively ridden by a seasoned 50-ish year old rider. That rider for many past decades had often experienced the crazy thrills and a few damaging accidents that eventually come to riders addicted to the roar of the engine, the amazing acceleration and overwhelming speed most big bikes are so easily capable of. After surviving that history, I realized I had to take it easy . . . most of the time. Besides accident risks and death there is the serious penalty and cost of speeding and reckless driving tickets.
That was until about year 2003 when I started taking Saturday or Sunday rides with 2 or 3 other customers that happened to be amateur CCS racers: http://www.ccsracing.us/about.html
We rode the woodsy and sometimes desolate areas of curvey/hilly northern NJ and NY states where traffic and police patrols were sparse. Besides being crazy fast, these guys were excellent riders on bikes that were professionally set up. It was a few of those NY state mile plus, huge mountain climbs where a half dozen rides with sustained 1/2 throttle plus high RPMs in the lower gears made my OilHead literally stop burning oil!! It seems that the chrome steel piston rings running in a cast iron cylinder liner have a very slow break-in that will not be completed if the engine never sees sustained (up-hill) heavy throttle combined with very high RPMs. The bad part is that the excess oil burning creates heavy combustion chamber deposits that effectively raise the compression ratio, which at some point will cause pinging even with premium grade fuel.
If you lack a desolate place to speed up the break-in, your alternatives are repeated full throttle to near redline RPM uphill take-offs for several rides (hot engine please), until you see the oil consumption stop. Less likely is finalizing the break-in on a track day "ride".

On another note, The Rotax made engine in my 2009 F800ST has never needed oil added, even during the break-in period. It did not require crazy riding to break it in. At the 1st oil change the oil level dropped only half way between full and add on the dipstick. After that, it barely drops at all and I was able to do this with the dipstick/filler:


Past 72 now and having a wonderful wife I need to live for, I have been riding near legal speeds almost all the time, with the ability to consume a tank of gas without using full throttle or exceeding 5,000 RPM because it is really not needed to excell in traffic, yet it is still a wonderful experience on the little silver Beemer.

Addressing the original question, NO to synthetic oil in an OilHead -until- the engine is broken in and stops using oil!! After that a full synthetic is best for an air cooled engine.

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