I have a completely rebuilt engine with around 850 miles on it. I am thinking it's time for synthetic oil. When are you supposed to switch to synthetic after the break in procedure?

 

Aren't you suppose to use synthetic off the line with MINI because of the supercharger??

 

You would be fine switching now. The only reason you run heavy blended or dino oil for the break in is to suspend the break in debris until the first oil change.

You should probably get that oil and filter out of there anyways to get the debris out.

Don't jump to a real thin oil just yet, stick with a 10-30 or 10-40 synthetic for the time being.

 

I'd go about 1000 miles for break-in, though if you do a search on "break in oil" or the like you'll get vastly differing opinions. Seems 1000 miles of mixed driving, getting harder and harder as the miles pile up, should about do it for breaking in the motor. Switch to synth then, I'd go 5w30 ish and listen to how comfy the engine feels. If it gets loud on 5w20 then stick with the 5w30.

Having a rebuilt engine means you may (or may not) have the really close tolerances these engines had when built, hence the break-in.

 

Ask the techs that did the re-build.

 

I'm pretty confident that all we are supposed to run is 100% Synthetic.

 

I think our TRITECs can happily run on dino juice, but why?

 

I had two techs and both disagree with each other! One says put a few thousand on it to let it fully wear in before the switch and one says you will be fine right after the first oil change. That's why I'm asking the NAM community

 

Good point. Remember, we're talking a new hand build here - tolerances will be different and break-in not the same as a new car engine. Personally, vary the speeds and loads, working up to 100% load after 1000mi. Change it after that to synth.

 

At 850 miles I'd say close enough.
Do the oil and filter change.
While peoples' opinions vary widely on this, I change the oil and filter every 3,500 miles, or when the oil looks dirty.
Wasteful? Maybe, but I put a high price on peace of mind!

 

The rings are seated in 300 miles or less.

That is the ONLY item that should be giving off any debris. There is no break in for bearings or seals.

 

There are syn oils that have higher zinc and phosporous compounds which act as synergist lubricants during the critical break-in period. 1,000 miles should be OK.

 

synthetic is always a good idea. do it!

 

slickfast, with high respect and as a fan of synthetic oils I agree in general. I believe (and it's a belief only, as this is the internet, through which I cannot see, feel, smell, measure or test the engine in question) that the OP's engine is about ready for a good dose of both synth and throttle.

In specific, however, the initial break-in lubricant needs to allow parts to "seat", specifically rings, but also other rotating parts in the engine. After that initial break-in, you want it as slick as snot. During, there needs to be a period of "synergistic lubrication" (AKA "wear"), just enough to get everything married up nice-nice. I like dino oil for break in, primarily because it's cheaper and it's only in there for ~1000 miles anyway. Also, various assembly lubes used in a manual assembly need to be dissolved and "washed away", break-in oil is good for that.

Opinions vary on how break-in happens and how long it takes (Mini recommends 1100 miles / 500km, some engine builders say "run it like heck from hour one", YMMV). The generally-accepted break-in is to vary the load on the engine, starting relatively easy and working up to 100% over a period of time/mileage, making sure all parts get up to operating temp during the duty cycle. Don't do too much too quickly, and getting the engine to operating temp (20-30 minutes plus per cycle, it's best to observe an OIL temp gauge and get to 180-210+ deg F) is key. Oil temp is a better indication of engine operating temp - it's closer to the action.

Enjoy!