5W/20 vs 5W/30 motor oil???

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Oct 30, 2005
South Dakota
From what I have gathered here, the only reason many car manufacturers are switching to 5W/20 motor oil is to boost CAFE numbers. This may help an auto manufacturer look good over the whole spectrum of autos that they sell. For the consumer, however,the use of 5W/20 only boosts fuel economy a few tenths of a mile per gallon. There may be nothing "wrong" with 5W/20 motor oil, but if the benefits are so miniscule, why use it and take the chance of compromising protection? I have switched to using 5W/30 in my Grand Caravan due to a consumption issue that I am trying to resolve. I will probably stick with 5W/30. Has anyone else switched to 5W/30 in a vehicle spec'd for 5W/20?
Thousands of posts on this subject. Some will tell you to do a "search", others will chime in. On some vehicles, the mileage increase with 5W-20 is noticable. IMO if you can gain mpg and a little kick in the butt dyno and still get great protection....why not? The UOA's seem to be spot on time after time.
I use 5w20 because it is a superior oil. My engine is spec'd for 5w20 so I have no fear using it. I don't officially recomend 5w20 in an application which is was not spec'd for but there is plenty of posting here where 5w20 was used in a non-spec'd application and it did the job with exceptional results. If 5w30 makes you happy and feel good why question it? As far as 5w20 being used for CAFE only, that is hogwash. CAFE is only one factor of the many involved.
I still feel Ford started using 5W-20 to spec a better quality oil to protect their interest with lease vehicles. The original Ford 5W-20 required much more stringent testing and the API specs in place at the time.
Is there any testing we know of that gives specific numbers for MPG gain using 5W/20 in comparison to other weights? I am not personally questioning the protective value of 5W/20, but I know that it is a concern raised by some here. When I raised the question here regardin MPG gains, the only answer that I recieved was that it was "a few tenths of a mile per gallon". It would be inresting to see some specific comparative data using different weight oil in the same engine.
In our Odyssey I am now using Mobil 1 5w-30 in the summer and Mobil 1 5w-20 in the winter. I just feel a little better about it. I don't think there is anything wrong with the 5w-20, I think it takes advantage of the improvements in dino synthesizing techniques to get excellent protection from a lighter oil. I also wonder about the added advantage of using less viscosity index improvers in a 5w-20 spread vs. a 5w-30 spread. I think in the next couple of years we will have a lot more information on this as cars run with regular oil changes on nothing but Motocraft 5w-20 hit 200,000 (or don't as the case may be). The Motocraft is just an example, substitute any other 5w-20 there.
Not this again! UOAs of 5w-20s look great. Members here must have millions of miles on 5w-20 with no problems. Many of us have reported increased gas mileage with 20 weights. There ain't much difference between a 20 and 30 weight. Any one have anything else to add?!?
Originally posted by Chris Meutsch: Clyde65, where are you now when we need your valuable, well-educated opinion on this topic? [LOL!]
Perhaps he's vacationing in Banville. [Wink]
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