Quote:
Originally Posted by OK-944
John...I'm close to installing my engine ('87NA944) which I'd rebuilt and subjected to my own (DIY) Sunnen AN-30 paste cylinder refresh...much as I gather has been done on your 924.
So I'm very curious as to how you plan to break in your engine. I've been a bit over the map on this, but my current thinking is as follows:
First Oil Fill: 10/40 Dino (detergent). First Run: 20 minutes high idle (2K RPM). Drain Oil. Reason for detergent oil - help to clean rebuild residue.
Second Oil Fill: 10/40 Dino (non-detergent), possibly with zinc "break in" additive. Second Run: Take it on the road...and do about a dozen aggressive accelerations/decelerations to set rings. Drain Oil. Reason for non-detergent oil - to help promote proper bedding in of rings. Zinc additive just for this run...as this run is aggressive and I want to protect tappets. (Possible change - use straight 30 weight oil for this run?)
Third Oil Fill: 10/40 Dino (detergent). Third Run: 500 miles normal driving. Drain Oil.
Fourth Oil Fill: 10/40 Full Synthetic (detergent). Engine Break In Complete.
So...how does this sound? And what are your break in plans?
Feel free to share comments, and/or to question my sanity. Thanks!
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OK944: yes, my engine got some expert Sunnen treatment from HondaDustR but then he put ca. 30K miles on it. All I did was pop-off the cylinder head after a moment's madness made me think perhaps I'd f'd it up (I hadn't). So this motor needs no break-in.
That said, I much less intense about this kind of thing than you, and I mean no disrespect in saying that. I did do the full-monty rebuild on my SC's engine and therefore followed break-in protocol on it. There was the first oil/filter change after the first start/breaking in the cams. Then another, maybe around 500 miles. I didn't use any special break-in oil, just 10W/40 Rotella then and for the next couple after that. I only switched to 15W/50 Mobil 1 maybe at around 6K miles because it's so closely priced to dino oil now.
I know this is a source of much disagreement (understatement) but I personally believe using super-duper oils in non-racing air-cooled 911's or 944's is a waste of money. My SC had been fed Castrol GTX all it's like - religiously every 3K mind you - and at 183K miles the main bearings were still like new. (GTX is a run of the mill dino oil.)
Where are synthetics mandatory? In your late model daily driver, for one: today's production engines are not only machined to incredibly tight tolerances, but also use engine oil to maintain turbos and effectively utilize it as hydraulic oil, to actuate cam timing mechanisms and the other fascinating doo-dads that make today's I.C.E.'s so remarkable. The passages in these mechanisms are tiny ... coking in the oil leads to their rapid deterioration. And at the light oil weights required - 0W/20, etc - I believe synthetic recipes are the only to make those possible.
The shorter version: for your 944, don't over-think it; in the words of Bob Marley, "Everything is Gonna Be Alright". And with 15W/50 Mobil 1 with good zinc content selling for ca. $27/5 QTS, I guess we can have our cake and enjoy it, too.
best regards,
John