I am nearing completion on my freshly rebuilt 2.8L.

Wondering what weight oil to use. Obviously going to use conventional oil durring break-in. 30wt, 10/30, etc. I am leaning toward 30wt or 10/30, but wondering what others recommend. I haven't found much on the subject, and its probably more of a personal preference/opinion as to what makes you feel more secure for first start.

I'll use the absolute cheapest 5w30 i can get my hands on and will change it after the initial run in, then again after the initial drive, then at about 200km and 500km. Then again at 1000km but i switch to a quality oil. At 3000km i switch to synthetic and start with the 5000km routine.

This is what i do and by no means am i a profesional but it keeps the oil fresh and as clean as can be for the breakin period.

I used what I was planning on using for the long term.

1st change, after initial break-in (I think that was only 20-30 miles)
2nd change, after 500 miles
3rd change, after 1000 miles
4th change, after 2000 miles
5th change, every 3000 miles unless using synthetic.

If memory serves me correctly, that's how I did it and it is still working just fine.

as a Manager of an auto service center may I offer the following recomendation.

Run 10/30 for 100 miles, change oil & filter,
Run 10/30 for 500 miles, change oil & filter,
Run 10/30 for 1000 miles, change oil/filter,
Run 10/30 for 2000 miles, change oil/filter,
Run 10/30 for 3000 miles, change oil/filter,
Use regular oil 10/30 untill you pass the 12,000 mark. Then switch to synthetic name brand 10/30 and keep changing your oil/filter,even synthetic, every 3,000. This will alow you engine parts to set in with regular oil. Synthetic is one of the best things to do for your engine life. You just don't want to do it before the engine breaks in. Running synthetic for extended periods, like 5,000 miles is doing about as much good of job as running regular oil and changing at 3,000 miles. I change my synthetic at 3,000 and it is so clean I keep it and use in my lawn mower.

Same weight as you'll run the rest of teh engine's life, just change it LOTS.

Consider running a mineral based oil for up to the first 10,000miles or so. Gotta make sure everything 'beds in' fully.

The synthetic will then basically STOP time for your engine Just put in new Mobil 1 and filter every 3kmiles as long as you own the car.

Best!
Ben.

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Ben Cannon
88 Formula, T-top, Metalic Red. (2:13.138 at Sears Point) "Every Man Dies, not every man really Lives"
88 Formula, Northstar, Silver, In-Progreess. -Mel Gibson, "Braveheart"

I tend to recommend using a petroleum based oil for break in due to some parts like the piston rings that sometime have hard time seating with synthetic oil. I usually use HD30 for several oil changes up until about 1500 miles then switch to whatever oil you intend on using be it regular 5w30 or synthetic.

Phil

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GTDude
25 years GM experience

Buy a new Corvette and it will have Mobil#1 5W-30 that is good enough for me. Mobil#1 is the best.
Don

The Corvette was changed to synthetic to make use of synthetic's high temp charateristics. It was determined cheaper to use Mobil 1 than install an oil cooler on the Corvette. A very small % of Corvette owners take their car to the track so GM provides for them with the oil cooler which is replaced with the synthetic now.

GM knows what synthetic is good at and uses that to their advantage ( profit ).