The Federal Trade Commission sued several companies (including Slick50) for making that claim. After a court hearing, and much expert testimony, it was declared false - starting your engine causes no more damage than normal running.

troy

Reminds me of the old claims that "starting your car uses the same amount of fuel as running the engine (idle?) for 10 or 20 minutes". If that were true, Hybrids wouldn't work AT ALL !!

Replaced my poor, beloved 2005 with a 2007 when a tree fell on it.

(For a Honda Insight)My manual suggests that I buy 0w20, yet it says that that's no good above 100 F. It usually stays above 100 F for a couple of months here in the summer.

I have been using 5w20 in the winter and 5w30 in the summer and I typically drive long distances. I have gotten 71.9mpg over the 70k miles I have driven my Insight. It did seem that the 0w20 might have gotten me up to 5mpg better(seemed to matter less the really long runs), but I never tested it in a scientific manner.

The logic makes sence though. If I'm understanding the numbers correctly, it's thickness as it relates to temperature. Intuitively, it seems that the oil would be matched just below 100 F(outside temp, while the car is hot), and when cool or anywhere up to that it would always be thicker, the two oils converging at below 100 F.

I have noticed in the summer, just before I switch to 5w30, the mileage gets much better(not running the A/C). I wasn't sure if this was due to less friction or to the seasonal blend differences in gasoline or both.

-Senrich

ahh, but that WAS true...for carburators. Remember having to pump the gas 2x before starting?

Probably true; I think the crux of the argument which is often missed is that starting puts the engine in a transient state, when all the piece parts are by definition moving through non-optimal conditions on their way to steady state operation. This puts the engine at greater risk of failure. Starting itself does not damage the engine; it places the engine in a state where it is more likely to be damaged. If you look at maintenance histories for industries that use large machinery, the majority of failures occur during startup/shutdown or other transient state- sudden loading/unloading, etc.

Its akin to saying that walking on a highway kills you faster than not going out there. The act itself doesn't kill you; it places you at a higher risk of getting killed by something else.

Yeah, but starting is not the only transient condition. So is reving from 1000 to 3000 rpm & back to 1000. Reving your car from 0 (off) to 1000 is no different than any other REV transition.



Slick 50's ads claimed "when you start your engine, there is no oil, and you are rubbing metal-against-metal." Several automotive engineers stood before the court and said that's not true. They said the oil is designed to cling to the metal, so that it's never dry. They also pointed out that oil contains ZDDP to protect the engine under extreme metal-on-metal conditions.

So the court declared Slick 50's ads to be false.

troy

Jason:

I can't speak for all hybrids, but my insight is a 3 cylinder very small engine which starts and stops fairly frequently and runs cooler than an ordinary or bigger engine. It's not the Integrated Motor Assist that's the issue, it's the smaller cooler more efficient Internal Combustion Engine part. Yea 'oil for hybrids' doesn't makes sence. 'Oil for small cool engines' makes more sence but then that'd probably confuse people.

-Brett

That's not entirely true. When you turn the engine off (autostop), the water pump stops as well. However the cylinder head, spark plugs, valves, pistons, and block all have excess heat that needs to dissipate. That's why the fan comes on AFTER you turn the key off, and it also comes on if the autostop has been active too long. There will be some convection cooling in the water jacket and radiator, and the aluminum block will also shed some heat from the air flowing across it. Due to the "heat soak" problem on these engines, stopping and starting all the time, I am surprised that Honda hasn't specified that the oil must be synthetic, regardless of whether it is 0w20, 0w30, 5w20, or 5w30, just for the better high temperature properties of synthetic oils. Also, the synthetics more closely maintain their viscosity ratings.

Also, the smaller engines in our hybrids are not really any more efficient than similarly designed large engines relative to their displacement. And more efficient engines have to run hotter, since all internal combustion engines operate on the principle of thermal expansion of gases. The greater the heat rise, the more expansion and combustion pressure to power the pistons down their cylinder bores. What makes any hybrid so efficient is that with a reasonably aerodynamic vehicle, cruising uses very little power. I read once when GM brought out the Chevy Citation, it needed 12 horsepower to MAINTAIN 55 mph. It is getting up to 55 and being able to accelerate for passing and such that requires all the extra power. Our hybrids use the electric systems to provide the power for acceleration. The gas engine is barely larger than needed to keep the car moving at constant speed. That's also why your fuel economy is so crummy in stop and go traffic, even with autostop and boost. In fact, our little engines have to work their pistons out to climb hills or accelerate past that slow semi on the freeway, resulting in the CVT revving the engine all the way to redline, or the downshift lights in the manual trans recommending third or second. All that hard work also makes them run a lot hotter. If you've ever watched your temperature guage, it gets up to "normal" really fast in the morning, even in winter.

The main reason for the 0w20 is that 0w20 weight oil uses less power to pump it up through the engine. It also flows more easily into the tight tolerances Honda and Toyota have designed into their engines. This is the same reason that all new GM and Ford vehicles recommend either 5w20 or 5w30 oils instead of the older 10w30 or 10w40 from years ago. The lighter oil uses less power, triggering better fuel economy. It is true the improvement is minor, but every 0.1 mpg counts when you're selling 500,000 cars and they have to reach a certain average fuel economy for your company. What with all the trucks and SUVs, it is amazing that GM, Ford and Chrysler can even meet the current C.A.F.E. standards.

I still remember the 20w50 oils!
Which, by the way, may still recommended for worn out engines operating in the summertime.

That will sweet this way we can get better MPG and be cleaner.