Quote:
Originally Posted by Daox
Seeing as how I am keeping this car for the foreseeable future, I'd rather not experiment with questionable oils. The transmission in the car is going to be modified and I'd like to not jeopardize the longevity of the transmission. Id rather take a couple percent hit on FE than shorten the life of the transmission.
The whole point of this mod is to improve short trip mileage. Putting excess engine heat to use is the method. I should have plenty of extra heat once the engine block is insulated. Super fast warm up is what I'm after for the engine and drivetrain to eliminate the cold start losses. The engine is going to be insulated either way just to have super fast warm up times. So, why not put the extra heat to use for the transmission?
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Basically a high viscosity oil at higher temperature is the same oil as a low viscosity oil in lower temperature. Critical viscosity is determined at the highest possible temperature. So the chosen oil grade has to be so thick, that it will survive driving up a mountain in a hot weather with full engine power. This may happen at low speed when air flow is low. Original oil grade is chosen like that. Most likely that means, that usually the oil is too cold to reach the optimal viscosity and an ecomodder will go anywhere near to the critical temperature.
I like the idea. It would be great if the temperature of a gearbox could be regulated. Heat regulation is just not an easy task to do. One of the main problems is that there is no excess heat in engine coolant when it is needed the most and the last thing we wan't is to slow down engine heating process. When the engine is hot, the gearbox is already quite warm and the possible benefits of gear oil heating are mostly lost.
If I would build an oil heating system, I would give a serious thought to an exhaust heat recovery system. Exhaust gasses are hot from the start. Toyota Prius uses this system with great results. The cabin heating system in a Prius performs extremely well in cold temperatures. Also preheating with an electric heater is a nice idea in cold temperatures.
If I was you, I would choose a low viscosity oil with a good viscosity index rating. A low viscosity synthetic oil would give you a lot of those benefits you are looking for. Everything is possible, but everything should be just fine. I googled a bit and found some promising oil grades. A 70W/75 or 75W/85 if your car experiences high load situations. With high load I don't mean highway cruising.
http://www.penriteoil.com.au/POS/GO_POS.pdf
How about reversing everything? A low viscosity oil and an additional cooling system to avoid the viscosity to drop too low? Or a temperature sensor and an extra coffee break when using a high power level a long time.