Need some 10w-40 help

Holy smokes- Is 10w-40 really bad for an engine because of all the VI improvers in it. I was under the impression it would help with a higher mileage engine. I am using motorcraft now in my Silverado with 128000, and the motor seems to run better with increased mileage even over the 10w-30. Please help me with this issue- I know that the cold weather issue with 10w-40 will have to be addressed but for now it seems like a good deal for me.
 
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Well, it sure wasn't a problem at one time, that is before the EPA and all the other liberals got into the action. I don't think it will hurt a thing, in fact, I believe in a thicker film cushion. BUt, just my opinion.
 
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With the advent of Group II base oils, there isn't as much of a problem with 10w40 as there used to be. Nevertheless, if the same base oil is used in making Brand A's 10w30 and 10w40, the 10w40 will have more VI improvers added. Conoco, Pennzoil, Havoline, Chevron, and Motorcraft all use hydrocracked and isodewaxed Group II base oils in their 10w40 oils. As long as you don't try to run the oil too long, any of these should do fine. (The only way to know for sure how well the oil holds up is to do a UOA.)
 
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yes there is was the problem of causing piston ring sticking .I remember pulling down motors that used oil and all the other problems associated with stuck rings,the rest of the motor would look fine . Usually easy driving all the time allows the gunk to build up and make the rings stick. The time frame was around 1975 to 1980? [ June 22, 2003, 12:20 AM: Message edited by: Steve S ]
 
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quote:
Originally posted by Steve S: yes there is was the problem of causing piston ring sticking .I remmember pulling down motors that used oil and all the other problems associated with stuck rings,the rest of the motor would look fine . Usually easy driving all the time allows the gunk to build up and make the rings stick.
The biggest problem GM engines had in the late 70s and early 80s (and the reason GM specefically forbade the use of 10w40) was premature cam lobe wear. This was before roller cams, so the lifter to lobe interface was a very high shear area.
 
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quote:
Originally posted by csandste: So, why wouldn't the same amount of VI improvers apply to GM's favorite: 5W30?
Well, the simplest answer is less vis spread: 5 to 30 is a 25 pt spread; 10 to 40 is a 30 pt spread. Hence, all else being equal, the 5w30 would require less VI improvers. Also, 5w30s generally start out with higher VI base oil blends, so that's another plus in favor of the 5w30 requiring even less VI improver. Also keep in mind that GM didn't start requiring 5w30 until most of their pushrod engines had gone to roller cams.
 

vvk

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I have seen similar results using xW-40 instead of xW-30. Smoother engine, lower fuel consumption. Europe uses xW-40 almost exclusively, you will have trouble finding xW-30 there, except for some 0W-30 that meet some of the latest manufacturer specs.
 
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I think Motorcraft 10W-40 is a very good choice for an older high mileage engine. I agree that the problem with too many viscosity index improvers in 10W-40 motor oil is mostly a problem that existed past. I would rather put a slightly thicker motor oil in a vehicle than have to constantly add oil. With an older vehicle that is consuming oil or if you are having low oil pressure I would think that you would have less engine wear with a slightly thicker oil. [ June 24, 2003, 02:19 AM: Message edited by: Sin City ]
 
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June 19th 1990, just over 13 years ago I took delivery of a brand new F150 4x4 I had built for me. 302 efi v8. I ran it on 10-40 pennzoil for 25K then went to amsoil 10-40, occasioanlly tried QS 10-30 and M1 10-30 syn, and now use castrol 10-40syn. She now uses 1qt per 1500 miles. I wrecked it right? well let me finish the story, I have 214000 miles, with original EVERYTHING, even ball joints, track rod bushings and tie rods, and I have towed with it since birth - 3500lbs of bayliner for the first 8 years, 5000lbs of chris craft since, 6500lbs+ of tractor for the last 4. best **** money I ever spent. change the oil every once in a while and you cant kill a ford. 10-40 is FINE. regardless of temp. (given that we dont live in siberia)
 
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