Quote:
Originally Posted by shadrach74
Good deal. Can you explain why you installed a 160df thermostat? No one (including those that sell them) has been able to give me a reasonable and scientific based answer as to why they are beneficial. Is there some advantage to having a longer warm up period?
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OK, here goes: The thermostat sets the baseline
minimum operating temp for the engine; it is the temperature the engine returns to when running at a steady state (road speed air flow across the radiators). Because of the convoluted design of the M96/97 cooling system, particularly the engine passages themselves, these engine's typically run a bit hotter than the temperature at which the thermostat opens. As the result, with the OEM stat opening at 186F, it is not unusual for the engine to run 210-215F at steady state on a fully instrumented 986 (forget what the dash gauge say, they are well known for being both woefully inaccurate and non linear). Because of the cooling system layout, at that temp the engine is actually much hotter in some internal areas, and as the oil is always hotter than the coolant (even though the engine uses a oil to water heat exchanger).
Changing to a 160F stat tends to lower the steady state coolant temp to around 175F, and more critically lowers the oil temps by over 25F, which the oil likes much better (UOA's before and after have shown the oil actually shows better parameters for longer distances between changes with the 160F stat). And on a base car, adding both the 160F stat and the "S" oil cooler (nearly twice the capacity of the base unit) improves the oil life even more. In essence, lowering the coolant and oil temps translates into improved life for both the oil and the engine.
And once and for all, cars with 160F stats
do not warm up more slowly; in fact, the tend to warm up more
quickly as the warmed coolant starts to flow sooner, not later.