Power loss with Heavier Oils

[Hapuna Beach]

Does anyone know the average HP loss going from a light oil to a heavy oil? Lets take a small 4 cyl engine; how much "loss" of HP is there between running a 5w-20 v/s a 5w-50 oil? Is there a large difference based on engine speed/load? Hapuna

 

[Schmoe]

I've noticed a difference going from a 5W-20 to a 5W-30 in my 02 V6 Accord.

 

[Patman]

quote:

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Originally posted by Schmoe: I've noticed a difference going from a 5W-20 to a 5W-30 in my 02 V6 Accord.

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Which brands? You really shouldn't have noticed much difference at all, since your viscosity probably only changed from 8.5cst at 100c up to 10.5cst. That 2cst difference wouldn't show up as more than a single horsepower, maybe two. Even if you went from an 8cst oil to a 12cst oil, it probably wouldn't lose you enough power to notice. Going from 8cst to 17cst though, THAT would be noticeable. The average person usually can't discern between a 5hp increase or decrease on their cars in the SOTP meter. [ July 17, 2003, 09:31 AM: Message edited by: Patman ]

 

[Scott_in_WI]

quote:

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Patman: The average person usually can't discern between a 5hp increase or decrease on their cars in the SOTP meter.

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Wouldn't that be dependant upon how “sensitive” their “seat” is?

 

[Schmoe]

Patman, yes I know I brought this up before when I switched out from the 5-20 to the 30's, but I'm here to tell you THERE is a difference. My wife even mentioned it to me BEFORE I told her I changed viscosities. I know, according to specs and all that good stuff, no difference would be noticed unless the seat is sensitive but I've noticed it, my wife has noticed it and the tach is running higher. I know I sound like a blazing idiot or the village is missing the idiot, but it's there. But, no leaks or anything, so I'll probably stick with Pennz. 5W-30 or jump ship and go Mobil 0W-20.

 

[tenderloin]

Of course there is a difference. HP and MPG can and do go down. I have noticed it more in smaller engines, but also in V-6 and V-8 engines. Currently my son is using the German Castrol 0W-30 in his Focus Zetec 2.0 DOHC. The MPG is down nearly 2 MPG compared to the usual Synergyn 0W-20 or even dino Motorcraft or Castrol 5W20. The butt dyno also tells there is a diffence. I also have seen many times ET's at the drag strip change with "lighter" weight oil. Many teams in oval racing also use a "lighter weight "qualifying oil" to get maximum speed....... [ July 17, 2003, 11:02 AM: Message edited by: tenderloin ]

 

[Bror Jace]

Patman, you sick, twisted dude. You’re probably gonna break the 7,000 post mark before the day is done! As for horsepower loss, I think it depends, depends, depends … Some engines are more particular than others when it comes to viscosity preference/tolerance. I would expect that hydrodynamic drag penalty to be worst at higher RPMs so an engine with little torque that builds its horsepower at higher RPMs is probably going to be the hardest hit. Drag often goes up exponentially, not merely numerically. Rough, general estimate is 1-4% loss (in horsepower and probably fuel economy as well) going from something like a 5W30 to a 10W40 or 15W40 for most engines which never top 8,000-9,000 RPMs. --- Bror Jace

 

[csandste]

I can see a slight drop off in MPG going from 5W30 to 10W30 although I prefer the latter. Could some of this be a switching to summer formulated gasolines? I note a huge difference in going from gas purchased in St. Louis to gas purchased in rural areas. Some of these specific urban blends can be real power suckers. Also ethanol, while increasing octane, lowers power. [ July 17, 2003, 11:43 AM: Message edited by: csandste ]

 

[jason07-1zzfe]

Yeah, RL says about 1-2% HP per grade difference with their oils. I definitely didn't feel it. In fact the 10w40 seemed smoother an possibly more powerfull than thier 10w30. Maybe high mileage and ring seal is a factor? Secondly, I am now running 10w30 superflo with RX. (don't ask) HTHS is lower than any other oil Ive run before (3.1) Yet it is the hottest running oil so far. So much for thinner being cooler. I guess the Syn base does make a difference. 10w40 RL (4.8HTHS) ran cooler than 10w30 superflo. We are only talking 7-10F MAX, not a huge differnce but real nonetheless. This superflo is not giving as stable pressure either and power delivery has noticeable peaks and valleys at WOT. So I am really trying to take it easy on it.

 

[James Chow]

I switched from Valvoline 5w30 to M1 Delvac 5w40 in my '01 prelude...fuel economy improved by maybe 5% (overall improvement was from 27 to 31 mpg, but probably 1-2mpg was the non-MTBE fuel used here). Personally, I wouldn't run 5w30 unless you live somewhere where it's cold...I heard the main reason why more carmakers spec 5w30 these days is that's what they use to boost the CAFE numbers in EPA tests, and the gov't requires the same weight of oil be spec'd and sold at the dealership. For example, in the case of toyota trucks, toyota specs 5w30 in the US, yet heavier weight oils elsewhere. Personally, I wouldn't go below a 10w30 during the summertime, maybe a 5w30 if you live in the NorthEast for winter. [ July 17, 2003, 11:52 AM: Message edited by: James Chow ]

 

[QuadDriver]

dyno testing has shown (and im betting quoted here somewhere also) that thinner oils do bring a pony or two on the dyno. however, this is due to reduced pumping losses from the oil pump, frictional losses would be second order at best and likely not measurable. it does not have a strong correlation to wear. intersting sidebar: ever prime a motor with a drill? a 1200rpm no load drill that develops what 1/4hp? 1/3? will get about 600rpm, which translates into appx 1200rpm engine speed (cam/dist/oil pump rotation is half that of crank rotation for a 4 stroke) so it it takes 1/4 hp to pump the oil at 600rpm....what does it take to pump at 3000 rpm (half of say a 6000 rpm redline) - and its not linear! but rather is proportional to the square of the rpm!

 

[Steve S]

The most noticable loss in using a thicker oil will occur in the lower rpms where the output of the engine is the least. Although pumping losses will occur at all rpm's. Too thin not good, too thick not good . It is interesting that an engine may seem to run better with a certain viscosity . I don,t know what it may mean ,I have noticed it. Is it the sealing or the cushioning of the oil film?.

 

[Patman]

quote:

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It is interesting that an engine may seem to run better with a certain viscosity . I don,t know what it may mean ,I have noticed it. Is it the sealing or the cushioning of the oil film?

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Actually, with a thicker oil, it absorbs the sound more, so your engine will often be quieter and run smoother, making some people automatically assume that this is the best thing for long engine life. Slick 50 has that same effect too though, and we all know the horror stories with those products.

 

[Steve S]

Patman Slick 50 is different than going up or down a grade, 10w30 to 0w or 10w 40 for example. Would the cushioning be better as to less vibrations. Remembering too thick bad, too thin bad.

 

[Quick_lude]

I went from M1 10w30 to 0w40. No noticeable difference in hp or fuel economy.

 

[sbc350gearhead]

This may be like comparing apples to oranges but.......Car Craft did a test last year comparing oils on a performance ford engine (390 IIRC)with well over 400HP. They started with a conventional 20w50 as a baseline. They gained 10HP by changing to a conventional 10w30. They gained another 10HP by switching from the 10w30 to mobil 1 0w30. Like I said, comparing synthetics to conventionals in not exactly scientific (especially in a built to the hilt motor).

 

[QuadDriver]

quote:

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Originally posted by sbc350gearhead: This may be like comparing apples to oranges but.......Car Craft did a test last year comparing oils on a performance ford engine (390 IIRC)with well over 400HP. They started with a conventional 20w50 as a baseline. They gained 10HP by changing to a conventional 10w30. They gained another 10HP by switching from the 10w30 to mobil 1 0w30. Like I said, comparing synthetics to conventionals in not exactly scientific (especially in a built to the hilt motor).

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looks to me like <5% over a serious amount of grade drop...

 

[moribundman]

I went from Syntec 5W-50 to M1 0W-40 in my Audi 2.8 12v. The latter oil is labeled as "energy conserving," but I have noticed neither better gas mileage, nor more power with the M1. Oil consumption, at about a 3/4 quart every 10k miles, is higher with M1. Go figure... [ July 17, 2003, 05:38 PM: Message edited by: moribundman ]

 

[Quick_lude]

quote:

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Originally posted by moribundman: Oil consumption, at about a 3/4 quart every 10k miles, is higher with M1. Go figure...

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I'd kill for my engine to consume .625L over 16,000km! Unless that's a typo?

 

[moribundman]

Nope, no typo. Before I switched to M1 0W-40 I had to add maybe 1/4 quart tops to keep it topped off between 10k mile oil changes. That means that with M1 oil consumption more than doubled. I know it's still not much, but it's more than I'm used to. [ July 17, 2003, 06:18 PM: Message edited by: moribundman ]