Break-in oil

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Mar 7, 2004
Southwestern Ontario
Ok, we know there are some manufacturers that recommend leaving the factory oil in as long as possible to ensure proper engine break-in (Honda). There are also those who do not recommend switching to synthetic early in the engine's life. What about doing a semi-synth first oil change and then switching to full-synth the next time?
I like quicker changes with a new engine. I usually do a 500 mile change then a 3500 mile change and then a 6500 change. The first two I use dino because its cheap. The last I go to synthetic which gives everything time to break-in. However based on gas milage and power my new Miata did not fully break-in till about 20,000 miles. I'd just stick to dino for break-in. Nothing to lose doing this.
I left the factory fill in there for 1500 miles, then switched immedately to M1 5w-20 on my wife's civic. Been running it ever since with zero problems. Better than stated gas mileage and smooth runnin.
FWIW, when I bought my Honda new, the dealer mentioned that there was special break-in oil in it and not to change it until it's first scheduled oil change. Then a few minutes later he stated that all Honda's used in Texas should follow the severe schedule for oil changes. Severe schedule is 3750 miles and regular schedule is 7500 the question then became do I leave the break-in oil the full 7500 miles? Since I take anything a dealer recommends with a grain of salt, and I believe a few short OCIs are good when a engine is new to get any of the left over crap from manufacturing out, I changed it at 3K and went directly to Mobil 1 and changed it again at about 6K. My reasoning was, anything the break-in oil was going to do, it would do it by 3K miles. UOA has shown that the break-in oil is most likely just the "new" 5w20 oil formulation with a heavy add pack of FM/AW components. Further, I believe that most myths concerning using full syns for break in have been dispelled with current engine technology. My 2 cents. [ May 04, 2004, 12:33 PM: Message edited by: 427Z06 ]
You can put synthetic in as soon as you want. Vettes come out of the factory with Mobil 1 in them. No reason others couldnt either really. But rest assured, your engine will not be harmed because you switched to synthetic early.
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