Break in oil after top end rebuild

[85343]

I am in the process of assembling the top end of my 95 R1100RSL after a valve job and replacing the rings. The bike has 80000 miles and one cylinder was a little low on compression. Exhaust valve guides were replaced along with all the seals, no other parts were needed. The machine shop said if I had waited any longer I would have needed new valves. I asked the BMW dealer service manager about break in oil after a top end job. He said he really didn't have an answer for me. He said BMW recommends dino oil for break in. He advised me to ask the machine shop that repaired the heads. The machine shop owner said use dino for 6000 miles because I installed new rings. I checked my owners manual and there is nothing about dino v synthetic oil during break in or when to switch to Synthetic, nothing. Many new cars today come from the factory with Mobil 1. I have been using Mobil 1 since I got the bike with 25k on it. The inside of the engine was so clean it looked brand new. I use Mobil 1 in everything with an engine. Does anybody have any scientific data that supports the dino for break in school of thought? Do the newer owners manuals advise against synthetic for break in. What would be different in the new cars coming with Mobil 1 from the factory that they can use synthetic for break in? Is dino for break in a belief that was repeated so many times that it became a fact in many peoples minds. If it is required why, doesn't my owners manual indicate that?

[PacWestGS]

Way to many questions, but I think there is just one to answer.

IME the use of standard (dino) oil is that it does its job of lubricating bearings and other moving parts without creating a superslick film on the cylinder heads. It is extremely important for the rings and cylinder to have enough friction for them to 'wear' into each other during the first 2-min to 2-hours of use. Synthetic oils don't allow this as well, and may actually lead to some pretty permanent scaring because the rings don't seat. Also, it's cheap enough that you can run it for break-in and then change it after a short time.

I don't know this to be a fact for any manufacture in the high-end auto field (outside of Corvette), but I think those engines are hand-built, tested and pre-run on a stand before they ever get to the car. So whether they do that first run with synthetic or not I don't know.

My 330ci came with synthetic oil and it's first oil change and service isn't 'scheduled' for 15,000 miles. I just got told to flogg it at will, from the dealer the day I bought it, with 22 miles on the odo. 12,000+ later there isn't a hint of anything wrong. (Was the engine broke-in before it left Germany? I don't know)

It won't cause any damage to run the dino oil for break-in and then go back to synthetic after the first oil change.

I remember, when I was doing small block chevy engines that we would add "Marvels Mystery" oil on first start up. ???

EDIT: Regarding 6000 miles, that is so all the other moving parts can get to know each other. Since you only did a top-end rebuild you'd be pretty safe to go back to synthetics on the first oil change 600 miles or less. Also, remember "Lots of loading and compression cycles on the rings after warm-up"

Doc

[Boxerkuh]

I think what you should do is treat the rebuild as a new engine. My recommendation is that you run "regular" oil and drop it after 500 or 600 miles, then run regular oil again and change it after 2,500 miles. Run that oil through and go back to the regular maintenance schedule. I would not recommend running synthetic oils until you have about 12K on the rebuild.

I have gone back and forth between regular oil and synthetic oils. I ride an airhead now and change my oil every 2,500 miles and have gone away from synthetics... I do run synthetics in the rear end and tranny because I change it every 5,000 miles.

No hard evidence, just food for thought.... :eat :drink

[rinty]

Kurt:

Last spring I bought an '02 1150 RS with 1000 miles on it that had belonged to BMW Canada. One of their employees told me not to switch over to synthetic until it had at least 20,000 km on it. Oilers can take a really long time to break in.

Rinty

[PacWestGS]

Guys and Gals he breaking in the pistons/rings and valve seats. I don't think his crank and main bearings are going to get any better after 80,000 miles of use. That should in effect be done after about 20-min of riding.


:bikes

[soffiler]

Guys and Gals he breaking in the pistons/rings and valve seats. I don't think his crank and main bearings are going to get any better after 80,000 miles of use. That should in effect be done after about 20-min of riding.

SFDOC: It is seating the rings in the ultra-hard Nikasil cylinder bores that is reputed to take thousands of miles.

[PacWestGS]

OK Thanks for the clarification, see what I know nothing :D

[riderR1150GSAdv]

IMHO just ride the bike like it has a new engine for the first 600 miles and change the oil. Then ride another 3K and change oil/check valves. Repeat at 6K and thereafter ride like you stole the thing... :D
The piston rings need to be seated in the bores and only time will do that. You don't have to baby the engine as if it has no miles on it, but give it a few smiles before doing a trackday :stick :wow

[PUDGYPAINTGUY]

Nikasil is what Superman uses as a tooth pick....hard stuff...lol

[PacWestGS]

interesting article in the March 'Motor Trend' mag about break-in from professionals in the engine building business.

Pg. 34

Worth a read.