[JFP in PA]

Originally Posted by blue2000s

Actually, I've read a study that found low temperature operation can form acids in motor oils, and high temperatures can cause oxidation. There is an optimal temperature where both effects are minimized at about 90C, or 194F. So there seems to be a "too low" range and a "too high" range for optimum oil longevity. I don't believe I'm wrong at all, but I'd be happy to be educated on the subject.

Well, we've been running the LN stat in six different customer's cars for over a year now, regularly checking a variety of parameters, including running full UOA's, and the oils (2,500 to 10,000 miles between changes) continue to look very good. And, by-the-by, the normal oil operational temps on these cars, even with the LN stat, are typically well over 200F.............the major difference being that with the low temp stat, they are staying 20-25F cooler than they were with the OEM stat………………


I'd also like to understand from you how an engine that runs the coolant in the 200F range under steady state would notice the difference between a thermostat that opens at 160 vs one that opens at 180F.

Simple, actually, the stat controls the minimum engine temp as well as at what temp the cooling system has full flow (stats open gradually in response to temp, not all at once). The LN stat is at full flow in the low 170’s, while the OEM unit does not see full flow until nearly 210 in most cars. As the result, a car with the OEM stat will run (steady state cruise on a 72-74F ambient day) about 210-215. The same car (and day) with the LN stat, the car cruises at 177-179F coolant, and the oil temp dropped over 20F as well. Tiptronic equipped cars also saw a concomitant drop in their ATF temps as well. Because higher engine operating temps are focused on emissions, not performance; lowering the operational temps improves volumetric efficiencies, not unlike using a cold air intake to improve charge density. A cooler engine also allows the DME to use more timing advance without detonation issues; which is an additional benefit to those running remapped DME’s. On Charles Navarro’s otherwise stock base (Tiptronic) Boxster, changing the thermostat from the OEM to the 160 netted an increase of 5 HP and about 4 Lb Ft. of torque at the wheels during back to back dyno runs using 93 octane fuel………volumetric efficiency does matter