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What anecdotal evidence(Iam not even sure what that word means)
It basically means knowledge gained through the observations of various stories told. I usually go for the ones that seem to be verified by independent sources, since I am in no way a chemical engineer nor is my degree in a technical field...
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is there that heavier oil causes problems. I have known people that used 20w50 forever or a straight 30 or 40 wt in Pennsyvania without problems.
I'd say that there is little evidence that heavier oil causes any problem in most engines. I've personally have had 20W-50 in an engine (basically an 80s vintage Mazda 1.6L which called for thicker oil and 10W-40 was the thinnest preferred oil) in the dead of a Buffalo winter, and noticed no significant problems directly related to the weight, not at start up, never.
My point is - what is the problem with using lighter oils where the application specifically recommends them? Just because you have a large V-8 doesn't necessarily mean that one has to use a heavy oil in a modern engine machined with very tight tolerances. Indeed, a thinner oil is shown to lubricate such engines better...
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Everyone knows Ford has issued TBs, they started the 5w20, then bragged they were saving X amount of fuel and stopping X amount of tons of pollution etc...I want to hear where thicker oil caused any significant problems,
Well, if a thinner oils saves you gas without causing problems and a thicker oil doesn't cause problems, but uses more gas over time, why not go with the thinner oil?
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because I dont believe it causes anymore or less than thin. It still comes down to common sense of your ambient temperature what wieght oil to use, because it is going to effect the viscosity.
Maybe. But you may be wrong. If you read that thread I linked/bumped on police Ford Crown Vic's, you'll see where I posted that a Florida police dept. had their MC filters shooting off the stem because they were using SAE50! Also, one guy related that a few engine failures in his Crown Vic fleet were related to the switch to 15W-40. Who knows? But I think it's safe to say that you're safer using 5W-20 in these engines than you are 20W-50. Though, using a PAO synthetic like M1 0W-40 may mitigate that somewhat...