Engine Break-In Oil Sequence Idea

[OK-944]

Not for a 911…but for my 87NA 944, the engine from which I’ve just finished rebuilding - top to bottom, all seals, bearing shells, rings, etc.

I also did a DIY (alusil) cylinder reconditioning process with Sunnen AN-30 paste…and while I won’t go into detail about this here, I will say that getting rid of the AN-30 residue was a total b*tch - and I’m actually a little paranoid that I may have left some behind.

So here’s my idea…that I begin the engine break in process with a DETERGENT oil - and do the first, 20 minute high idle with this, then dump this out and go to a NON-DETERGENT oil to take on the road to set the rings…followed by the usual 500 miles, another oil dump/fill, etc.

While I know that detergent grade oil is not recommended for the ring setting process, my fear about going right to a non-detergent oil for the first idling run is that this might facilitate some unwanted abrasive action of any leftover Sunnen paste residue.

My question then…assuming that detergent oil would indeed help get rid of unwanted residues more effectively than non-detergent, is would this procedure in any way compromise the next, non-detergent oil process of breaking in the rings?

[VFR750]

I don’t think a detergent will make a difference if the oil is put into a new engine and will be drained after 20 minutes.

The oil will look crappy because of the assembly lube and ring seating.

I hope you washed out the bores thoroughly to get rid of any residual cutting fluid. Otherwise the cams, rockers and bearings might be affected.