Thread: Synthetic

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Getting close to putting fluids in a new 350 crate motor. Anybody using synthetic oil in their 32???

I run synthetic oil in almost all my engines, but I do the break in time on new engines with dinosaur oil. On street engines, I usually run about 2500 miles on the engine before I make the switch to synthetic..

Originally Posted by Dave Severson

I run synthetic oil in almost all my engines, but I do the break in time on new engines with dinosaur oil. On street engines, I usually run about 2500 miles on the engine before I make the switch to synthetic..

Wait wait.. My friend (he gets a really big head about shit and if you contradict him he basically gives you the bird). Anyways he kept telling me not to use synthetic in my new engine... I used Regular straight oil for 1500miles for the break in and went to synthetic blend. He still to this day tells me that that engine spun a rod because of the type of oil I used.
Was I alright using synthetic? or was I wrong...?

Originally Posted by weylinthedirty

Wait wait.. My friend (he gets a really big head about shit and if you contradict him he basically gives you the bird). Anyways he kept telling me not to use synthetic in my new engine... I used Regular straight oil for 1500miles for the break in and went to synthetic blend. He still to this day tells me that that engine spun a rod because of the type of oil I used.
Was I alright using synthetic? or was I wrong...?

One of the biggest reasons people spin rod bearings is in correct rod prep,not enough bearing clearance.
The rod under high load conditions becomes egg shaped or elongated what this means is it pinches in the middle which will cause oil starvation.

rings won't seat with synthetic oil. rings must be fully seated b4 switching to synthetic

The rings will seat with synthetic oil, just may take a bit longer. Depends on the hone of the cylinders and the type of ring used. I've ran synthetic on a number of race engines with narrowed low tension rings and had no problem getting them to seat. On a GM crate motor though, dinosaur oil will speed the ring seating process along.

Originally Posted by Dave Severson

The rings will seat with synthetic oil, just may take a bit longer. Depends on the hone of the cylinders and the type of ring used. I've ran synthetic on a number of race engines with narrowed low tension rings and had no problem getting them to seat. On a GM crate motor though, dinosaur oil will speed the ring seating process along.

dpes the ring compisition have anything to do with it also? like cast, Molybedum, Chrome Moly?

Sure does, the harder the ring surface, the longer the seating time, normally. Perhaps the biggest variable is the finish on the cylinders. We just got hooked up with a new machinist who has a state of the art computer controlled power stroke hone. He also has a ton of experience on getting the finish on the cylinder to match the ring material and tension of the rings.... JMO, but I've also found the narrowed rings seat quicker and also have the benefit of less friction between the rings and the cylinder wall resulting in quicker throttle response (though a very slight change) and a lower operating temp in the cylinder area. Spent half a day with the guy and was amazed at some of the combinations he used and the dyno results of them... Now if I just understood half of what he was telling me!!!!!!

I'm going to run moly rings in my 200 I6 ( rebuilding, turbocharging and converting it to TBI EFI ) is there any additive such as EOS I could use to speed up ring seating?

I'm no big fan of additives. The correct hone on the block done with a good machine is IMO still the best for ring seating...

only reason they say not to use synthetic for break in is because the rings take longer to seat than with dino oil, as Dave said. now you broke the engine in on dino oil, what weight and how cold was it out? that could have starved new bearings of oil from it being too thick if it was str8 weight

Your bearing didn't spin from the fact you were using synthetic vs crude oil. Some other factor caused that failure. Could be improper installation, oil starvation either on fire up or during operation, bad tolerances, etc etc.

Tell you "expert" friend that there is a reason many new cars (including Corvette) roll of the assembly line with sythetic and that it is the recommended oil throughout the car's life. Even in the Marine industry, where I work, many engine manufacturers, like Volvo, have a sticker on the valve cover telling you to use synthetic.

One differerence between crude and synthetic is that batch after batch, sythetic is consistently the same. It is man made. Crude, being made from dead dynosaurs, can vary in composition batch to batch. That doesn't necessarily present a problem, but is just the way it is.

Like the guys said, use crude for the first 1500 to 2500 then if you want to, switch to synthetic.

Don

I changed to synthetic in a rebuilt 360 at 3000 miles, and it leaked at both crank seals. Changed back to dino, and it slowed the leaks but didn't stop. That's the only bad experience I've had with it, but I don't use it any more, mainly because of the price.

Originally Posted by R Pope

I changed to synthetic in a rebuilt 360 at 3000 miles, and it leaked at both crank seals. Changed back to dino, and it slowed the leaks but didn't stop. That's the only bad experience I've had with it, but I don't use it any more, mainly because of the price.

Is it/isn't it bad to change back?

Originally Posted by Itoldyouso

Y
Tell you "expert" friend that there is a reason many new cars (including Corvette) roll of the assembly line with sythetic and that it is the recommended oil throughout the car's life. Even in the Marine industry, where I work, many engine manufacturers, like Volvo, have a sticker on the valve cover telling you to use synthetic.
Don

with the corvette though remember its got 16 hours on the motor when it comes out of the factory so that they verify rings are seated bearings aren't gonna spin and dumbass customers dont destroy their new engine by racing the car the day they buy it

Originally Posted by R Pope

I changed to synthetic in a rebuilt 360 at 3000 miles, and it leaked at both crank seals. Changed back to dino, and it slowed the leaks but didn't stop. That's the only bad experience I've had with it, but I don't use it any more, mainly because of the price.

yeah thats the one downer i've noticed with synthetic oil.... if it was gonna be a minor seep with dino oil.... is gonna be a gushing river with synthetic