Hi all,
I recently had a rebore on my M20 and a new oversize piston.
I always use high class oil
Now I'm advised to use low quality oil for some time to get the piston run in.
Otherwise, that is not going to happen with good oil.
Is that a good idea ?
Any thoughts..?
How would you know what a "low quality oil" is? I can't think that any oil manufacturer would advertise their oil as "low quality".
Not wishing to start another oil debate, but I use Morris Golden Film monograde 40 in all my bikes. I would just use the oil you've always been happy with. As I'm pretty sure that they haven't invented an oil yet that will give completely negative wear. Ron
email (option): ronpier@talk21.com
There is a running in oil. Millers, among others do it.
I have never bothered though.
Morris's Golden Film sae 40 as detailed by Ron is a good choice...This oil was my recommendation for all the engines I rebuilt in more or less 20 years running a business doing engine/gearbox overhauls...and, of course, I've used it in all my own bikes.
Looking at the bigger picture when the cost of an engine rebuild is considered, oil cost is irrelevant and personally I wouldn't give any creedance to the information you have been given...It certainly doesn't align with my experience..
I recommend using the running in procedures as described by BSA and would advise frequent changes during the running in period..
I do mine at 200 miles, 500 miles and 1000 miles and every 2000 miles thereafter..and though it's not the only factor my bikes are very reliable...Ian
email (option): ian@wright52.plus.com
Cannot remember where I read it but the reasoning goes like this.
If you use a good quality oil at first start up it will coat the rings with friction reducing chemicals which sounds good but actually means they never get the chance to wear and bed into the bore so in the long term. So you end up with an engine that will never be as oil and gas tight as if could have been.
Hence use cheap oil that does not have these or running in oil and you will get the best out of your rings/engine.
Makes sense to me, but please do not shoot the messenger!
email (option): larkesrATgmail.com
I read that many years ago. When you think about it, it makes sense.
Can't say I agree with that myself...I don't think the oil consumption figures could be any lower than they have been on the two bikes I have owned for 30-40 years...Also, low compression has never been an issue either, which might be expected if the rings weren't bedded in properly...
Further, I haven't found excessive 'blowby' on pistons either..I'm certainly the type that would make changes if I had any suspicion it was necessary and I can safely say my attitude is based on personal observation and experience, not blind dogma. (Just in case anyone was going to suggest I'm a 'luddite!):laughing: ...Ian
email (option): ian@wright52.plus.com
Fixing a glazed bore is always cheaper than fixing a seized one, so I go for a running in period with frequent oil changes rather than cane it day one. Last bike I ran in (my M20) I used Super Universal Tractor Oil as I had lots of it.
email (option): sacombsashtrees@hotmail.com
BMW approached this problem a bit differently. They recommended to allow the freshly prepared cylinder lining to rust slightly before dry assembly. I believe this works well to allow the rings to bed-in. But like Ian implied, the actual reasons for this are lost to time and may well be based on conjecture.
On the other hand, standard advice for unit twins recommends cheap oil and a short brisk first ride for the same reasons, changing to higher quality oil after break-in.
Didn't some of the distributors of full synthetic oil say for a while that engines should be run in on mineral oil as the high spots would never ease off if their wonder product was used from new ? The idea that they put about was that their oil was so good you'd have to ride at running-in speeds forever :-)
Too much std oil will also cause the rings to take longer to bed in.
Decades ago I had my ear bent about installing rings dry and have been doing it this way ever since.
Once upon a time we had a product called "running in oil "
Running in oil was a very high zinc , very high detergent , low viscosity oil designed to get between the dry surfaces because we did not have assembly lube back then.
The single most important thing when running in regardless of which oil you use is not to leave the engine sitting in your drive idleing for 20 minutes while you frigg around with the carb.
This is the perfect way to glaze the bore and that will add a good 1000 miles to the run in time.
email (option): bsansw1@tpg.com.au