Griff

I didn't say they were using the 15-50wt. Lighter weights are of course used because of the tighter tolerances.

Not looking to stir stuff up. I've heard the rumors about not using synthetics with roller cams. I've just never heard anybody actually say that they had failure caused by it. Merc used to say not to use synthetic. They have since changed there minds since they now make a synthetic blend.

nocigarette

Ever go to the races and look inside peoples trailers?????
thats the oil i run....mobil 1

JBoat

Oil temp is generally around 170 to 180. and it does take about 10 to 15 minets to get there.

Regardless of brands you all like my main concern and reason for the post was the oil weight. If it runs cooler, do I want a hevier weight or straight weight oil ?

I will stay with synthetic as I beleive it to be a better oil.

Wobble

I and many others here run Mobil 1 20/50. I have been using it for 7-8 years.

Check with your engine builder to see what he prefers, otherwise the synthetic 15/50 is good and the 20/50 better.

Your cooler engine will be fine with a multigrade. The only issue is whether your oil stays clean or gets cloudy from condensation.

Straight 50 weight will not lubricate well at start up in a cold motor(plenty of pressure but no flow). Some racers use it, but they also have oil tank heaters.

07DominatorSS

No, GM does factory fill all their Cadillacs, Corvettes and SS models with Mobil 1 0w-30. So does Chrysler on all SRT models and so does Roush with all his Mustangs. So, not sure where you get your information. If you're talking specifically about 15w-50, then possibly, but they do factory fill with Mobil 1. However, I would still use AMSOIL in those motors, Series 2000 Racing 20w-50.

07DominatorSS

You've got to remember too, it may be running cooler just for the fact you are using a pretty high quality synthetic. Therefore reducing friction and operating temps.

JBoat

I heard not to run a racing oil, as it has less aditives ot adtives that are not made to hold up as long. They are made for a few passes at the track then to be changed.

If you are going to go for several months with out a change as I do to stay away from race oils.

Rookie

iTrader: (4)

are synthetic viscosities rated the same as conventional? I thought they were different.

07DominatorSS

We've gone two years on an oil change on our 2004 Sunsation MCOB with a MERC 496 in it. It has about 180 hours on it. We use AMSOIL Series 2000 20w-50. AMSOIL uses the best additives they can buy, which makes their oils last longer. We also test the oil too, to make sure its good. We use Oil Analysis Lab in Spokane, Washington.

07DominatorSS

Synthetics will flow better, have colder pour points (quicker to the top end), and also create a higher film strength, therefore better protection. Not all synthetics are created equal. Synthetic blends are mostly still a petroleum oil, with some synthetic additives blended into them. Most Synthetic blends are similar to a cup of coffee with one creamer. The creamer being the synthetic properties.