Synthetic or conventional in fresh rebuild?

[UnexplodedCow]

Hello all.
I assume this question has been answered already somehwere else on the forum, but having dialup is not very conducive to forum hunting, so on with my question.
I have a 1990 Ford Escort LX. I just finished rebuilding the engine, and I'm wondering what oil to put in it. I thought of putting in synthetic oil due to its properties. I know it's better, but is it better during the break in period? And, if conventional oil is better, would I have any problems switching to synthetic after the break in period, say 3k miles? Oh, and what merits would having an oil cooler have? Any help and info would be greatly appreciated. Thanks all

Cow

[ghostguy6]

If you just rebuilt the engine you should have put some cylinder lube in the cylinders, that will protect the engine during the first few strokes until the oil from the bottom of the pan is circulated thoughout the engine. Synthetic oils have more additives to help keep the engine clean and the oil molecules are a little bit smaller so they work their way into the mircoscopic cracks in the metal to provide better protection. You can get away with conventional oil. As long as your not revving the shit out of it before you get it worn in you can use any oil you want, just be sure to match the grade to your car, since your in WV id say go with a 5-30 and you should be ok.

[curtis73]

I recommend using regular oil for break in. Critical parts have a certain amount of time to wear into each other; cam and followers, rings and cylinder walls, etc. Using synthetic these parts don't wear together as well.

I think there is a possiblity that synthetic is just as good or better for break in as regular, but I've seen the evidence proving the regular works. I just haven't seen proof for the synthetic regarding break ins so I stick with what I know works

There is no problem switching to synthetic. Usually sythetics can reveal weak points in very aged engines, like ring blowby and leaks, but nothing to worry about in a new engine. I started using synthetic on a BMW with 156,000 after 16 years of regular oil and had no leaks or blowby issues.

I like the regular oil for break in because it permits the wear that is supposed to happen, and I like synthetic after break in because it prevents wear from happening.

[UnexplodedCow]

Actually, I didn't replace the cam, but the lifters were. The original ones were extremely leaky, bad enough to where they caused a ticking at idle. And no, I won't be revving the shit out of my engine. I generally don't take it above 2500, although I won't be lugging either. If I shift at 2500 in my car I generally drop 800 to 1k in revs, depending on the gear, so nothing fancy. Besides, this is an Escort, not exactly something hipo. Any more info?

[curtis73]

What type of lifters do you have? Replacing just the lifters on a flat tappet cam is a sure-fire way to wipe the cam lobes flat. If you want an explanation I can give you one, but that is very inadvisable.

If they're roller lifters, you're fine, but flats need to have both cam and lifters replaced together because they wear together.

[UnexplodedCow]

I know that already, but thanks. Yeah, I have a roller cam, which is why I wasn't worried. The cam looked good, too, but I have thought about replacing it as well in favor of a higher lift one, but that will be later.

It's got the stock crank in the engine, too, but it's been cleaned up and polished. The block was also bored .040" over to take care of a gouge in a cylinder wall, so new pistons and rings to fit. The rods are stock as well, but I'm not worried about them either. New main and rod bearings are in the thing as well. New iron oil pump (stock is aluminum), and new valves in the head. The valve springs and rockers are fine.

Also, any ideas on what octane fuel I'd need to run with a higher compression engine? Stock compression for my car is around 135-155 psi....and the last time I checked the engine I was around 210-215. That was before I rebuilt the thing, so I'm expecting that again, but possibly more. Would 93 take care of it? I have a pretty primitive car, central fuel injection, so it's not exactly high tech on the knock protection. Yeah, I have a lot of questions, sorry.

[curtis73]

No problem Glad to hear about the rollers. No worries there.

You could maybe advance the cam by one tooth and see if your cranking pressures drop a little. I don't think the Ford will run that way since it relies on a crank triggered ignition, but honestly the last one I dealt with was an 87.

Depending on the cam specs, you might bleed cylinder pressure up higher in the revs, so the actual compression might not be too high. I say try whatever Ford recommended from the factory. You'll probably get some ping. I've heard that a good rule is run one higher octane than when you hear detonation. If you try 87 and it pings, but you don't hear it with 89, do the 89. If you get ping when its hot still on 89, jump to 91. My guess is that 91 will be more than OK.

[UnexplodedCow]

I'm not worried about the pressure, just the octane. Ford actually specs that engine to run up to 250 psi compression. I know that isn't the compression ratio, but it does give me a good idea of what I have. Stock comp. ratio is 9.0:1 on my engine, at 135 psi....but, like I said, the head is redone a.k.a. cracked and repaired. But it's stable, so no worries The engine ran before I tore it down, but burnt oil like crazy. The rings were way out of spec, and the pistons slopped in the cylinders.

[curtis73]

Gotta love American Metallurgy Let us know how the break in goes !

[Polygon]

The first time you run it after the engine is rebuilt I would run conventional oil in it for about 20 miles or so and then change the oil with some fresh conventional to help clean anything left from the rebuild out of the engine. Then I would run it for about 3,000 miles on the conventional before changing it and refilling with a full synthetic. Conventional oil helps parts seal better than synthetic.

That is just what I've always known to do.