I've broken my motor in for 7000 miles on dino oil 10W40.

The engine builder recommended 15W40 in hot weather and 10W40 in cooler weather.

If I switch over to Royal Purple Synthetic, will using 15W40 be a problem?

How much thinner is Royal Purple synthetic?

 

I would ask your engine builder. He built it within a certain tolerance and he will provide you the most accurate answer.

My engine builder built mine to use 20-50. He said I could change to synthetic whenever I wanted after it was broken in.

 

If read many automotive engineers say it doesn't matter. Porsches, Corvettes, Vipers, Cobra R's, AMG Mercedes and others come that way from the factory (Mobil 1). The Chevy engineer said that they found it actually helped (some long explaination, I'll try to find it) with seating the rings.

 

id be willing to bet that is a marketing deal or incentive.........mobil supplies it for dirt cheap and gets to say that auto manufacturers "choose" mobil because its the best.

 

Good reading http://www.syntheticoiltech.com/oil/...KeptSecret.htm

 

The only concern with using synthetics early in a rebuilt engine's life is ring seating. With modern machine honing techniques and ring materials, even that concern is normally eliminated.
Mobil 5W30 is good enough for a 400 horse ZO-6, its good enough for me.
I can see no use for increased bearing clearances, and an attempt to "fill" them with a heavy oil is a waste of time. Both Honda and Ford has reduced bearing clearances recently, and now specify a 5W-20 oil under the new GF-3 ILSAC spec.
I have never understood the idea of extended drain intervals, and there is no evidence that any engine needs greater filtration than that provided by the stock filter. Below a certain size, particulates do not cause wear. Chemical contamination and degradation dictate oil drain intervals, not particulates.

 

I swear by Mobil 1. My LT1 has 148,000 on it and doesn't burn a drop of oil between my 5,000 changes. I still run 5-30.

 

to quote brent from another thread
"This reminds me and I'll bring up something else... we don't "change" our 20,000 gallon plus turbine lube oil system. We constantly filter it. This oil gets used for 2 years straight (24 hours a day 7 days a week) then gets put through a centrifuge and used another 2 years and so on. Basically, just pointing out that oil doesn't get old or go bad... it gets contaminated. "

im guessing that unfiltered particles contribute to the "contamination" that ruins oil..............so the better filtration you can get, the better your oil will be.

 

It is not possible to compare a steam turbine lubrication system with that of a hydrocarbon fueled piston internal combustion engine. The operating requirements are completely different. Even gas turbines (turbojets) have different requirements.

In diesels, particulates (soot) do contribute, but are vastly greater in quantity than anything a modern gasoline engine will produce. No amount of filtering will change the chemistry of the oil, as filtering is strictly a particulate removal process.

Use good oil, of the appropriate viscosity and service requirement, synthetic preferably, and change it and the filter regularly. That's all there is to know.