5W30 or 10W30?

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Originally posted by TallPaul: If I expected this to happen I think I would want Redline Oil in my crankcase. What grades are listed in your owner's manual? That is always a good place to start. I do feel that a 10wXX is the way to go, probably a 10w30. How is your oil pressure? If running a bit low, you might be able to step up to a 10w40.
Actually, the answer would be 10w-40 or preferably 15w-40 if the bearing tolerances are acceptable. And, in FLA water pumps and AC compressors fail more frequently, so you may expect this to happen. I was running up from Naples on I-75, when my AC compressor started to seize, causing excessive heat and slowing my accessory belt, making the pump almost useless. When the alarm/light went off, I was doing 95mph, and there was nothing but vapor in my radiator. 15w40 saved my engine from cooking.
 
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Originally posted by c_rossman: ...My wife has a 2000 Dodge intrepid with the 2.7L V6. Very hightech engine that if it had 8 cylinders it would be larger than my 460 Ford!
If your wife's car had eight cylinders of the same bore and stroke as her 2.7L V6, it would carry a metric displacemnt of 3.6L. That translates to roughly 220 cubic inches - perhaps just a tad shy of 460 cubic inches?
 
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Originally posted by TheFuror: A service writer at the local Chevy dealer made it quite clear that in his not-so-humble-opnion, if GM recommends 5w-30, then that is what to run. He explained that there is more to it than ambient temperature, such as bearing clearances, etc.
TheFuror: You do realize this service writer was factually impaired, right? At ambient temperatures above freezing, you should expect a 5W30 and a 10W30 that are both within their respective grades to perform in *EXACTLY* the same fashion. We've had viscosity comparisons made on here between 0W30 and 10W30 oils where the 0W30 actually resists pumping more than the 10W30 does at room temperatures.
 
[QUOTE]Originally posted by TallPaul: Better than the All Climate and Synpower Oil Treatment would be straight Durablend IMO. I was thinking the same thing. As soon as I use up what I have left of the All-Climate, I'm going to switch to Durablend 10W30 on my Blazer. Durablend should also be fine to use on the wife's '04 Malibu, right? I'm going by the OLM on it at this point.
 
I am a life long Valve user and I have done UOA's on my '02 4.7l Dodge Ram and my wifes '03 Hyundai Sonata LX 2.7L V6. Do a search on my user name to find em. I have a UOA with 5w-30 All climate and a 10W-30 Dura blend. Both showed VERY similar wear rates and I would have been able to go about 4500 miles on each. The only real difference in the UOA's is the fuel % in the second report. That is due to short trips and not the oil. I think 10w's are still more shear stable though. Even those gaps are closing though. So I decided for the Colorado climate I face each year I will be going to 10w-30 Dura Bland [Cool] for the entire year. The cold temp pumpability is close if I remember for the 5w and 10w weights and a bit more shear stable as most of our driving is a 6 mile round trip to work and back with occasional trips into town(170+ mile round trip).
 
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Originally posted by TomJones76:
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Originally posted by TheFuror: A service writer at the local Chevy dealer made it quite clear that in his not-so-humble-opnion, if GM recommends 5w-30, then that is what to run. He explained that there is more to it than ambient temperature, such as bearing clearances, etc.
You do realize this service writer was factually impaired, right? At ambient temperatures above freezing, you should expect a 5W30 and a 10W30 that are both within their respective grades to perform in *EXACTLY* the same fashion.

I think it important to understand that the stated preference for 5w-30 comes directly from General Motors and that the service writer is basing his recommendation on that. The owners manual that I have for both a 1998 Silverado and a 2004 Avalanche state in no uncertain terms that the clear preference is for 5w-30 and to use 10w-30 only if 1) the temperature is above 0 degrees F; and 2) 5w-30 cannot be found. Having said that, I am not suggesting that I know the answer to this question. Indeed, I am still in a quandry as to which weight to run. Here's why: BITOG has many, many people (who seem to know what they are talking about) say that, as a general rule, 10w-30 gives significantly better protection than 5w-30, and as long as the temp is above freezing, to run 10w-30. Lots of other folks (who also seem to know what they are doing) say that 10w-30 is really obsolete, given the actual numbers, and that 5w-30 gives your motor all it would need, have a nice day. I have looked at several motor oils and at least with respect to most synthetics, the numbers between the two grades are very similar (40C and 100C vis, along with HT/HS). In the end, I suppose it may not really matter. I just am trying to keep this $30K vehicle running so my oldest can take it to college in 7 years. I know, we can only dream.... [LOL!] Thanx Bob W. a.k.a., "TheFuror".
 
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Originally posted by KW: I'll have to dig out some of my newer books but I don't buy in to the clearance thing at all. 1971 350 Chevy crank and rod. .0008-.0020 and .0013-..0035 1985 350 Chevy crank and rod. .0008-.0020 and .0013-.0035 Both have a rod side clearance of .006-.014
Here is some info. on my '99 Honda VFR: Rod, .0012 - .0030 Main, .0009 - .0020 Looks pretty close to the Chevy. I moved a few months ago but I'll dig around and see if I can find any info. on the Ford Mod. motors that spec. 5W20.
 
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Originally posted by KW: Here is some info. on my '99 Honda VFR: Rod, .0012 - .0030 Main, .0009 - .0020 Looks pretty close to the Chevy.
1997 Suzuki GSF 1200SV (Bandit) 1157cc inline four, air/oil cooled. Main 0.0008-0.0017 in Rod 0.0013-0.0022 in Service limit on both is 0.0031. Main bearing = 1.417 in Rod journal bearing = 1.495 in All this data would be a bit more meaningfull if it were posted in terms of (inch clearance/inchdiameter). Even without that, it still gives us a good indication that there isn't a big range on production tolerances from a 1971 Chevy to modern engines though. And since the MC bearings are roughly 1.5 inches and the car bearings are generally 2.5 inches or under, that wouldnt make a dramatic difference.
 
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Originally posted by MikeR: First, many 5w30 dinos, especially the "energy conserving" oils, seem to shear down to a 20wt within a couple thousand miles. While it could be argued that this is because 5w30's require more vii's and that they don't offer the protection of 10w30's, it's starting to look like they are designed to shear down to 20wt, thus the "energy conserving" status.
Does the same apply to Group 3 5w30s ? I'm currently using a Group 3 5w30 Castrol that is A3/B3/B4 rated. I can only assume that it's a thick 30w A3 rated oil to avoid shearing down to a 20w ?
 
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