Oil for break-in after top end rebuild 1982 GPz750

Any opinions about which oil to use for seating new rings? I usually use Spectro Golden 10-40. Works very well. Minimal wear after 87,000 miles. Just wondering if it is too slick for break in. Thanks, and Happy New Year, Mark

I'd use cheap store brand oil. 10-40/5-30. Dump it after 500 miles.
Steve

I used Rotella 15W-40 diesel oil after my recent ending rebuild.

I use that now after I dumped the cheap stuff. Doing another oil change and a tire change too. Just not burning oil anymore. Looking at those clutch plates, I could see some aluminum left over from the near cam chain disaster caused by that APE tensioner. The stock one is doing fine.
Steve

I've always heard to never use synthetic oil to break in an engine. The rings will take much longer to seat...I use cheap, dino oil and then switch to the good stuff (like rotella) after a few hundred miles.

Thanks for all of your input. All the best, Mark

swest wrote: I'd use cheap store brand oil. 10-40/5-30. Dump it after 500 miles.
Steve

Same thing I did except I added some STP to juice up the ZDDP content during break in. I think I used 10-40 Valvoline.

ThatGPzGuy wrote: I've always heard to never use synthetic oil to break in an engine. The rings will take much longer to seat..

I have read that a bunch of places. But I never saw any actual data to support it and the oil makers say it's baloney. I would never use synthetic for break in because I am too cheap to put in $40 worth of oil I am going to dump after 100 miles.

I have also never seen any hard evidence that fully synthetic oil is a problem for break in. More and more cars come with it from the factory. Yes, I know, new technology,water cooled et cetera.

What I find puzzling is guys who will spend hundreds or thousands of dollars on an engine rebuild in their most prized possession and then fill it with the cheapest oil available during the most critical moments of the engine's life.

I do it to seat the rings then puke out the oil with all the crap that's in it.
Steve

I think I'll go with Spectro 4 for break-in (non synthetic), and then switch back to Spectro Gold (semi-synthetic). Keep it in the family

If we are talking about just the rings, you don't want too much lubrication as it seems the problem with rings not seating is caused by to little load and/or too slick a lubrication. Perhaps it's the bigger clearances in an aircooled motor compared to today's water cooled engines, but it is certainly a common problem to find rings not sealing on rebored cylinders. On the Vintage Triumph forum there are a lot of threads where people end up with rebuilt motors that smoke and they advocate over there some specific procedures to ensure they seal, no idling and riding with plenty of load from outset.

The ZDDP is needed mostly for cam break in with solid lifters and also needed for normal running with solid lifters. The only thing to watch using a cheaper oil is if it's a car oil they can contain additives that can damage your clutch plates. Rotella is the best bang for your buck IMO, about $13 for a gallon and is often used as a break in oil because of the ZDDP and is also JASO approved which means it's OK for a wet clutch. The high detergent content of diesel engine oils are also good for keeping any contamination, following a rebuild, in suspension so it comes out when you change the oil.