I'm a great believer in synthetics (Mobil 1 for engine, ATF, diff, and occassionally Delvac 1), however after talking to fleet managers of UPS and FedEX, local public transportation company, as well as a United Airlines fleet manager for their flight simulators, and members of the PORSCHE club, all of these entities all recommend SWEPCO mineral-based lubricants ( http://www.swepcousa.com ) over *any* synthetic except in cases where you need LOW temperature pourability. These fleets even have an extended drain interval without using synthetics (upto 100,000 miles or 600 hours with a LOA program).

SWEPCO maintains that their products offer better lubricating properties than synthetics, and they are better than those in the synthetics by Royal Purple and Mobil.

By the 5-gallon pail (6-gallons for SWEPCO), SWEPCO 306 20W50 motor oil is cheaper than Delvac 1, but slightly more expensive than Royal Purple and Mobil 1.

Porsche club members have had great success, esp. with Porsche 928's that use the Mercedes 722 transmission.

I switched to SWEPCO 714 20W ATF, and *immediately* the shifts in our C36 tranny was much smoother (previous ATF oil was Mobil 1 ATF with 5K miles).

How can this be so?
My understanding is that synthetics were superior in every way, including lubricity?
If you start with high-quality "dino-based" stocks and high-quality additives, can you really beat synthetics?

Thanks in advance,

:-) neil
1988 360TE AMG