quote:Measuring the oil temp at only one point would tell you nothing then. You'd need at least two points of measurement. For what you're talking about, the ability of the oil to be a heatsink, you'd want a sensor right at the post-oil cooler pre-engine point and one right as the oil leaves the engine. The difference between these two numbers is how effective the oil is at picking up heat.
Originally posted by cryptokid: if a synthetic oil was truely better at heat exchanging then it would have higher oil tempatures. a syn is suppose to pull heat off the engine's parts. well this heat has to go somwhere! eventually this heat gets out through the surface of the engine and or a heat exchanger. but the heat has to get from the engine to the air. it travels its path via the oil.
quote:Wow, your the first person I ran across that actually measured their oil temperatures and found them so consistent. Maybe the value your reading is the dummied down value sent to the "idiot gauge". FYI, the "idiot gauges" they put on most cars today, barely move out of the normal zone unless the actual temperature is way above the nominal zone.
Originally posted by mountravlr: The thermostat and the radiator fan provide enough variation to render oil temp efficiency relitively meaningless, IMO.
quote:It seems plausible that the slower circulating 40/50 weight would have more time to absorb component heat, therefore raising its temp. Think about the cylinder walls(high temp area); a thick oil will spend more time there before it drips/is pushed off. [ July 24, 2004, 10:20 AM: Message edited by: 69 Riv GS ]
I had a 1996 VW Passat GLX VR6 that had an oil temp gauge and 10w-40/20w-50 oil was consistantly 10-15 degrees hotter then the 10w-30. 10w-30 idle was always about 202* 10w-40 212*, highway 275moh 10w-30 was 216-220 10w-40 was usually 228-234.
quote:I take that back. A lower viscosity fluid more efficiently transfers and dissipates heat. It's explained here.
Originally post by me: It seems plausible that the slower circulating 40/50 weight would have more time to absorb component heat, therefore raising its temp. Think about the cylinder walls(high temp area); a thick oil will spend more time there before it drips/is pushed off.
quote:All else being equal, 40 will only run a bit hotter than 30 wt. Not nearly enough hotter to make it the same viscosity as 30 weight. I switched my car from 5W-30 synthetic to 15W-40 HDEO. There isn't enough temperature difference to say for sure if it runs hotter, cooler or the same using a digital oil temperature gauge. You need some well controlled tests or need to really be a believer to see the difference in the real world.
Originally posted by zoomzoom: So 40wt will run hotter oil temp then 30wt, given this can we say that both oils will be at about same viscosity under higway driving conditions? Or in another words 40 wt will behave like 30wt since it is running hotter, if so what is the benefit of running 40wt in first place?