I recently rebuilt my 305 for my 85 Berlinetta. I am getting ready for an oil change. I told the mechanic that did most of the rebuild, that I was going to change to synthetic oil.

He had some reservations because synthetics were thinner and the rebuilt engine wasn't as tight as a brand new motor.

Are his concerns something I should worry about too? Should I stay with dino oil or switch to synthetic?

 

He doesn't know what he's talking about.

 

I might be a little concerned with him saying it isn't as tight. I wouldn't put synthetic in on my first oil change. I would wait for a couple more oil changes. My rebuilt engine has almost 7000 miles on it. I am thinking of switching to a synthetic blend and if everything goes good with that I will switch to synthetic.

 

On a freshly rebuilt engine (or a new car for that matter) you should run dino oil initially but it shouldn't be a problem switching to synthetic on the next oil change. The shop that rebuilt the engine on my Sentra SE-R roadrace car said synthetic oil doesn't allow a "fresh" motor to break in properly. They told me to drive it for 500 miles (I think ... maybe it was a little more) on dino oil then switch to synthetic.

 

not true, you can run Sythentic from the get go, look at vetts, M1 from the start, and i have from M1 from the start and there is around 10,000 miles on the engine.

 

yeah dino for the first oil change, then synthetic after.
thats what i did with my new motor after researching it for a while.

-brian

 

Hey Thanks everyone. I guess I'll stick with the plan for synthetic then.

 

Look at this lawsuit involving synthetic oils...


A federal judge has approved a settlement worth more than $32 million in a class action products liability suit against Mercedes Benz brought by owners of cars manufactured from 1998 to 2001 who said they were never warned that use of non-synthetic motor oils would cause premature engine wear.

Under the settlement, 351,439 class members will each receive a voucher worth $35 toward a scheduled service which includes an oil change, and Mercedes-Benz USA has agreed to modify its warranty to cover the costs of repairing any damage caused by the problem.

Now if that doesn't tell you something, i don't know what does.

WHOLE STORY HERE:
http://www.law.com/jsp/article.jsp?id=1048518273610

 

5-7,

Maybe she/he does know EXACTLY what he's talking about...

If the mechanic didn't take the time to properly fit the bearings, polish the throws and mains, fit the right thrust lash, or otherwise took shortcuts in the rebuild, there may be some trepidation in advising the use of synthetic lubricants.

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That link to the class-action Daimler/Benz site only tells me a few things:

1. Federal judges arent chemical or lubrication engineers;
2. Too many lawyers are STILL crooked, and Shakespeare may have had the right idea;
3. Mercedes Benz doesn't have the foresight/intelligence to prominently install awarning decal under the hood warning against the use of anything but synthetic lubricants (like some GM vehicles have);
4. Daimler/Benz presumed that owners in North America would be just like owners in Europe, and try to take care of their vehicle as best they can. They neglected to understand that Americans that are uninformed enough to go shopping for a Benz are probably also too stupid/lazy/uninformed to bother to read an owner's manual;
5. People who can't/won't read the maintenance recommendations in the owner's manual desaerve exactly what they get;
6. **** staff car purchasers deserve exactly what they get.

Being German/American, I have little tolerabce for those who want the "prestige" of having what they presume to be a superior product, when they don't really have a friggin' clue about the realities beyond the nameplate on the ugly-*** grille. I LOVE to smoke those 500s and 450 2-doors with my "inferior" American car. Either 1,300 feet at a time or beyond 160 MPH - just bring it on.

Louis Chevrolet was a Schweitzer who was smart enough to get the hell out of there long ago.

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5-7,

Reading back, you may be right, and I may have been mistaken. If the "mechanic" told him that synthetic oils are "thinner", he DOESN'T know what he is talking about. He should have his tools confiscated and go back to school, or go back to adjusting air pressure in tires and pumping gas. Someone who doesn't have the intelligence to tell you he doesn't really know the answer deserves everythinbg he gets...

 

This has nothing to do with the answer to the original question due to the fact his motor is allready broken in. But in case anybody every searches this thread out and then decides it's safe to break in a new motor with synth..

If you have a roller camshaft go ahead and break in with synth if you wish.

If you have a flat tappet cam, do the cam breakin period with dyno oil.. and maybe even some GM EOS additive. Synth is too slippery and the lifters may not spin in their bores. They need a little bit of friction at break in to start them spinning and wear in. If the lifters never start spinning then all you have is the lifter sliding on the cam lobe which will quickly wipe the lobe.

 

That's what I was thinking.

That is a very important point.

I still prefer non-syn for break-in of a rebuilt engine. New car - I'd change it over as soon as I got it home (as if that's going to be an issue any time in the near future).

 

That's exactly what I did. One had 7 miles on it when I got it. The other had 235 miles on it after the dealer had it in their inventory for about a month. To me, considering that the original factory break-in oil is cycled out after a run-in, and the refill was used for at least a little idling and moving the vehicle from train car to flatbed to hauler to lot to prep area, it's been run more than enough to set the rings. On rebuilds, after about 20 hours of operation, the oil comes out anyway. If the proper procedure for breaking in a flat tappet cam is followed (with break in lube and mineral oil, the oil at that point really doesn't need to allow for friction. Roller cams require even less time on mineral oil, if at all. Rings just aren't the same as they used to be, and hard chrome faced rings aren't the "nuts" like they used to be.

 

Nobody brought up chrome-moly rings--or mabye that's just assumed with a rebuild. I was going to start a new thread to ask the same question, but I'll just ask here.

It "seems like" the general concensus is that, as long as you're using a roller-camshaft, you should be okay to use synthetic from the get-go. I'll buy that.

However, I rebuilt my engine with Federal-Mogul chrome-moly rings, which I have been told on many occasions take particularly long to seat (compared to what, I don't know--what else is there?). Also, apparently the inferior lubricating qualities of non-synthetics actually helps to seat the rings properly. Thus, unless you want to go burning expensive synthetic, it's best to use dino juice to break in, and then switch to synthetics some time after that. I've always known that "some time" to be 500 miles.

As far as my situation goes, I've got exactly 500 miles on my rebuilt engine. I've been running Quaker State 10w30 in it from the beginning. I ran that on the inital break-in period, and after the first 30 or so minutes of running time, I changed the oil and filter (I actually had 2 initial break-in periods, but that's a long story). The stuff that came out was like a non-transparent blackish color, which I assumed to be due to normal blow-by associated with non-seated rings. The stuff that's in there now (which has 500 miles on it) looks okay on the dipstick, although probably a bit dirty for 500 miles (but not nearly as bad as the first change).

I can't tell that I'm burning any oil (and I don't think I've really burned that much since the rebuild). Would I be wise to put in the synthetic now--or should I hold off? (In other words, does the fact that I have chrome-moly rings make any difference?)

 

Royal Purple FAQ

How should I break in my racing motor with your oil?

We recommend using a quality mineral-based oil for break-in purposes. As a general rule, follow your engine builder's guidelines. On street setups, the rings should seat within the first three or four times the engine is brought to temperature. After the rings have seated, change to Royal PurpleŽ. It is not recommended to break in an engine using Royal PurpleŽ, as the film strength of the oil may not allow proper seating of the rings.

 

i never had that problem.....my engine was factroy new, not rebuilt, as in it had 8 miles on it and came out of a caprice in a high school shop. The shop closed down and i bought the engine....so i just ran M1 in it from then on....NOW my brother on the other hand just rebuilt my old motor.....so 30 min on 30w, fast idle around what 2500? starting it up a few times and letting it cool down...then change the oil and repeat.......then can he start using M1 in it?