I would appreciate any in put on a freshly built 1.7L and side shift 915 transaxle as to anyones' experience with synthetics. I will break in the engine with Castrol 30w. It will see some track time after proper break in. Thank You. Manolo

My understanding is that both are great oils and with a fresh rebuild you shouldn't have any leakage problems with synthetic. Jake Raby recommends Royal Purple oil - he has said in the past that during his test Royal Purple ran the coolest.

In the transmission I would run Swepco fluid. Our tranny synchros aren't designed for synthetic oil.

Probably won'r see any difference with the gauges we use. But a Dyno and more accurate gages may show some difference.
But both will do you well.

do you mean a 901 tranny, or what some call a 914 tranny

Both the 915 and 901 transaxles work better with conventional oil, the G50 transaxle works well with synthetic oil. Swepco 201 is a very good conventional oil and that is what I am currently running in my 915, but I have also had very good results just running 90/145 wt from the FLAPS. Based on my past experience and the cost of Swepco, I doubt I would pay for it again. There just wasn't enough improvement to justify the extra cost.

After break-in I really doubt you will be able to accurately detect any difference in performance between the two synthetic oils. Go with what is cheaper, easier to get, and less hassle.
I run mobil 1 in my six but that is only to protect the turbo bearings from getting coked up. If I wasn't running a turbo I would not be running synthetic oil.
Again, IMO the difference between a good quality conventional oil and a good quality synthetic oil in a normal engine is so small it usually doesn't make sense to pay the extra money for synthetic.

Just about all synthetics are good. I'd go with Mobil 1 since you can find it even if you are in BFE. All others might be an adventure to buy if you really need them.

Jake indeed stands by Royal purple, but said many times mobil 1 was the WORST synthetic for our engines... Valvoline was 2nd in his tests... I Use Valvoline full synthetic in mine...

I will need to use a synthetic since my engine has twin turbos. I worry about breaking in an engine with synthetic since in the past it has taken MUCH longer for the rings to set in (in a naturally aspirated V-8). I also worry about the turbos during break-in with a non synthetic. I have visited the massIVe website and was impressed with many of the details and experimentation. However, I would like to hear the reasoning for saying that Mobil 1 is the worst possible oil (synthetic?) for the type 4 engine. Synthetic oils are merely manufactured or synthesized using chemicals instead of being refined from crude oil. The result is a more pure, more stable oil base that can be engineered or designed to have a wider viscosity rating and resist thermal break down. Synthetic oils were originally developed for use in gas turbine engines. In most cases they are capable of maintaining their viscosity for longer periods of use and under much greater temperatures and pressures than petroleum products. No disresepect intended, but Mr. Raby's information goes directly counter to what many automobile manufacturer's and racing teams require in their vehicles. I am assuming that the Porsche GT-1 EVO twin-turbo charged flat six was running Mobil 1 and not just getting paid the sponsership for the stickers on its nose and tail. I believe Porsche does require Mobil 1 in some of their vehicles to remain under warranty, especially the twin turbo 996, but I could be mistaken. I also believe the Chevrolet Corvette ZO6 requires Mobil 1 to stay under warranty. I can get Mobil 1 at the HomeBoys, (Manuel, Moises, and Joaqine), which is around the corner. I can also get Redline at Home Mechanics Warehouse (PAW) which is somewhat farther, but if it is much better, I will give the extra effort. I have not see Royal Purple anywhere. I did see a episode of Horsepower TV where they were touting its increasing horsepower on the dyno. But like I said, I have not seen it for sale. In the past I have used Castrol Syntec, but I tend to blow things up anyway. I have never used Mobil 1 nor Redline in any of my vehicles. Just wondering about anyones' personal experience.

QUOTE (omanolo @ Aug 22 2005, 05:57 PM)

I will need to use a synthetic since my engine has twin turbos.

a twin turbo 1,7? interesting! how does it run?

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I worry about breaking in an engine with synthetic...

don't. use a good quality dino oil. you won't be on boost much during break-in. once the rings seat, switch.

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...I would like to hear the reasoning for saying that Mobil 1 is the worst possible oil (synthetic?) for  the type 4 engine.

dyno tests have shown it retains heat more than some others. maybe it's the thermal conductivity, maybe it's the total heat capacity. i donno. other synthetics have been shown to cool better. you can believe the test results, or not...

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Synthetic oils were originally developed for use in gas turbine engines... Porsche GT-1 EVO twin-turbo charged flat six was running Mobil 1... I also believe the Chevrolet Corvette ZO6 requires Mobil 1 to stay under warranty.

a T-IV is not a gas turbine, it is not a 911, and it is not a water-cooled V8.

i snipped the part where you talk about synthetics. there is no argument there. everybody's sold on them. Mobil-1 has been shown to cool less effectively in T-IV's than Royal Purple or Valvoline Full Synthetic.

(there may be an issue with cost-effectiveness in normally aspirated engines that do not need the extended thermal protection and do not take advantage of the extended drain interval. but that's a different issue.)

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I have not see Royal Purple anywhere.

Summit Racing carries it; i haven't seen it in my area either (but then i have 6-cylinder cars and Mobil-1 works just fine in those). Royal Purple is expensive - but so are built engines.

QUOTE (Sammy @ Aug 22 2005, 01:27 PM)

Swepco 201 is a very good conventional oil and that is what I am currently running in my 915, but I have also had very good results just running 90/145 wt from the FLAPS.

The Swepco rep was doing demo's at my show...I doubt if you would say that after the demo. The swepco climed up the gears while the cheap (and not so cheap name brand) stuff just sat at the bottom.

The moly grease demo was an eye opener, water and most greases makes soap...the Swepco doesn't mix with the water.
BTW take a blob of gease and hit it with a hammer....see what happens...the Swepco doesn't do that.

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Based on my past experience and the cost of Swepco, I doubt I would pay for it again. There just wasn't enough improvement to justify the extra cost.

What experiance? look, smell, taste, noise or real tests??

How much is a rebuild?