And I know quite a few Porsche owners who have sworn off synthetic, myself included. Especially true for guys who track their cars. Even with the heaviest weight synthetic, it thins too much at temperature causing oil pressures to drop dangerously low at the track.

All I know is that NONE of the engine builder's who do it for a living (at least none that I've ever used or talked to) ever recommend using synthetic in a newly REBUILT engine.

 

If your at the race track, you should probably be using a straight weight oil then, not a multi weight oil as your post suggest. If oil "thins" at running temp where its detrimental to the engine or its performance, you probably need to change weight.

Many engine builders come from old roots and old ways of thinking, but I can put down a list of builders though who also use straight synth from day one on new builds (race or street), so where does this leave the whole topic? Apples to oranges? Liquid cooled to air cooled? Auto to bike? I know I have never had a single issue of ring seal, or engine breakin that was in anyway detrimental by using synthetic. I have seen fried rings though from using dino oil upon initial breakin on more than one occasion on a vtwin air cooled engine.

 

Probably would be better on straight weight oil if it were strictly a track car. But, my car is driven on both the street and the track. SAE 30 has proven itself way too thin even for street use on my car. And, SAE 50 is too thick for cold weather use. For my car 20W50 non-synthetic has been the all around best choice (since break-in). Supposedly, 20W50 is about the same on the high temperature end as SAE 30 but, on my car, it doesn't seem to thin as much. However, I do normally run SAE 30 on initial break-in of an engine. Eventually, when I get back to tracking the car more, I'll probably run SAE 50 at the track and 20W50 on the street.

Apples to orange? Liquid cooled to air cooled? I don't think so. It's only been recently that Porsche was forced to go to water cooling on the 993s and 996s. And, it won't be long before you see the last new air cooled Harley Davidson. Even among the Porsche air-cooled crowd there's a long running debate over syn versus dino. Bottom line is, whether it's a car engine or bike engine it still needs lubrication. And, as long as there's dino oil available, the debate over dino versus synthetic will continue.

 

20-50w as suggested will act as a 20 weight at running temperature, so thats why you probably think its too thin if 30 straight weight is preferred in your application.

 

I think that's backwards. 20W-50 means 20(Winter) when cold, 50 when hot.


>>Multi-weight oils (such as 10W-30) are a new invention made possible by adding polymers to oil. The polymers allow the oil to have different weights at different temperatures. The first number indicates the viscosity of the oil at a cold temperature, while the second number indicates the viscosity at operating temperature. This page from the Sci.Electronics.Repair FAQ offers the following very interesting description of how the polymers work:

At cold temperatures, the polymers are coiled up and allow the oil to flow as their low numbers indicate. As the oil warms up, the polymers begin to unwind into long chains that prevent the oil from thinning as much as it normally would. The result is that at 100 degrees C, the oil has thinned only as much as the higher viscosity number indicates. Another way of looking at multi-vis oils is to think of a 20W-50 as a 20 weight oil that will not thin more than a 50 weight would when hot. <<

http://auto.howstuffworks.com/question164.htm

 

Yep, your right on that. I did get it backwards, but at running temp the oil is supposed to act as a 50 weight and not break down to anything less than 20 weight. The polymers are what make the 20w act like a thicker oil. Polymers due break down and as they do the oil is not supposed to thin past 20w.

In heavy duty racing applications using a thicker straight weight oil is still a better idea, straight 50 or 60 weight would be ideal, and that bears more importance than the synthetic label.

 

I just have to ask one more question and then I'll let this one go. If dino oil is so bad for motorcycle engines, as some here have implied, can someone explain to me why all Harley Davidsons (with the exception of the Screaming Eagles), come from the factory with dino oil? Perhaps it's because HD wants the engines to tear up so their customers have to bring them in sooner for rebuilds. Maybe we should all bring a class action law suit against HD for putting dino oil in our bikes at the factory.

 

$$$ Cost.

 

Let's see:

3.5 quarts of HD Dino oil at $3.95/quart = $13.83
3.5 quarts of Screaming Eagle Synthetic at $8.95/quart = $35.35

So basically, HD was willing to risk a $4000 engine (minimum) over $21.52 worth of oil. You're right. It all makes sense to me now.

 

You need to look at things from a wholesale perspective, not retail. Say HD saves an average of $5-10 wholesale per bike by using regular dino. Times than number by about 350,000 bikes per year. Thats alot of money saved and put back into their pockets. Regular dino oil is fine for HD motors too(Im sure their own tests have shown that its sufficient enough for their engines to survive the 2 year unlimited mile warrenty with minimal warrenty repairs percentages using dino), it just breaks down much quicker than synthetic and does not offer as much protection.