Forum Discussion
dodge_guy
May 02, 2015Explorer II
Wes Tausend wrote:
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Use 5w20. The thicker oils may not hurt the engine too much ordinarily, but they have a delayed circulation time in cool weather. This can cause lack of lube on overhead cam engines and damage camshafts and valve train.
It also turns out that the greatest benefit of pressurized oil in engines has been its ability to cool bearings. This, of course, takes a high flow rate to be most effective.
There is old wives tales still circulating around how thick oil can cushion bearings. Any modern day bearings that need "cushioning" are basically shot, usually galled by overheating, since the old, slow thick oils often failed at proper cooling. A bonus, fast flowing oil lasts longer now that it is not overheated by exposure lag under high heat stress. Oil thickens from heat as it ages and does not do as good a job cooling bearings. This thickening is one of the reasons automatic transmissions need frequent replacement lube, especially after abuse. Synthetic oils led the way to oils and blends that now resist thinkening.
Some of this knowledge became evident when it was noted how well automatic transmissions avoided wear with thin oils and how sensitive they were to cooling. This is opposed to manual transmissions that used to often use 90 weight gear lube, many of which now also use thinner oils.
Wes
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Maybe in cold weather (winter), but in the summer when the oil is hot and as thin as water that protection can break down. like I said, when I run 5W20 in my X in the summer and I`m towing when I pull into a campground and turn off the engine all that oil drains into the oil pan. now when you go to start it all that oil has to be pumped back up into the engine. mine would clatter for a couple seconds the next morning during a cold start with 5W20. with 5W30 I don`t have that issue.
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