Oil Viscosity

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Please excuse and ignorant question but why do today's modern vehicles specify this low viscosity oil ??? Many of todays vehicles run hotter than the older ones did but still recommend a 5W-30 Oil Is this something to do with EPA and Gas mileage ratings and are we actually doing harm to the engines by running such a thin oil ??
 
Do a search on "5W-20" and watch all the hits you get. This has been a long time discussion and will always be on this board. IMHO, I think the new "fangled" 5W-20's are too thin. However, UOA's have been showing up excellent in certain engines. The Ford 4.6 and 5.4 modular engines are showing very little wear using the Motorcraft 5W-20, which is a synthetic blend. I also think that there need to be some other tests on that viscosity because I just can't believe that stuff is the real deal. I run nothing thinner than a 5W-30 M1, which is actually like a thick 20 weight. I believe the switch to thinner oils is strictly a CAFE issue. Numerous reports have addressed this to be the case. But, like I said earlier, the 5W-20's are doing well. Particularly the Motorcraft, Pennzoil and the M1 0W-20.
 
quote:

Originally posted by Eddie:
I believe in data and not personel opinion when it comes to engine oils. If the manufactures recomend 0w20 oil then I believe that have generated enought data to back up the recomendation. Too many opinions are based on nothing but 10 year old ideas.

They may be logical conclusions as opposed to opinions. For instance, what is to be concluded by FoMoCo recommending 5w20 for the 4.6/5.4 in 2001 when they recommended 5w30 for the exact same engine for 2000?
 
Yes I have a hard time believing that thin oil is better but would not want to do anything to void my warranty. I use only Castrol GTX as I change it too often to justify synthetics
 
I believe in data and not personel opinion when it comes to engine oils. If the manufactures recomend 0w20 oil then I believe that have generated enought data to back up the recomendation. Too many opinions are based on nothing but 10 year old ideas.
 
I think the real explanation here is that these oils are formulated extremely well. Better than there 5w-30 etc oils. That is why we are seeing excellent results with them. It just shows how important oil formulation is vs weight of the oil.
Just price these oils and you see they cost more than 30 weight oills. You get what you pay for here, at least that is what I believe. It will take a while to convert me. If I purchased a new car that would then force the issue. UOA do tell the tale.
 
I've done some testing of high quality, 5w-20 and 0w-20 synthetic oils in hot climates ....

Based on the results I've seen, I'd use a 0w-30 synthetic in Ford/Honda/Acura/Mazda engines and NOT a 5w-20 - even if it was a full synthetic. With the xw-20 oils, you are right on the ragged edge when it comes to maintaining full flow lubrication in the bearings. A 0w-30 synlube "brackets" the SAE 5w-20 recommendation and provides better cold weather protection AND better hot weather protection. The GC, 0w-30, the Mobil 1, 0w-30 and the Amsoil 0w-30 are all better ways to go, for a car you intend to keep for 10+ years. The Redline 5w-20 would also be fine, but it's as thick as a 10w-30 in terms of high temp, high shear viscosity @ 3.3 Cp.

It's a no-brainer as far as I'm concerned, and I was predisposed to thinking that xw-20 synthetics would be just fine to substitute for 5w-30 and 10w-30 conventional lubes.

Tooslick
 
TooSlick,

I believe that you answered my question in another thread regarding using a 10w-30 dino in a 2004 Honda. The bracketing of 0w-30 make sense and going over 5,000 miles to get out the junk.

Great response.
cheers.gif
 
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