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Floorboard it - or downshift?

Keith: do a little searching for ‘hydrodynamic lubrication’ and you’ll find that low speeds and heavy loads do a double whammy on sleeve bearings.

You can also find comments from engine re-builders who can tell if an engine was lugged by looking at the rod bearings.

Since your claim: that heavier loads do not increase wear, is exceptional, perhaps it is you who should be showing us proof.

I would shift down until the RPMs were >3000 and the engine was easily handling the load. Driving at 1800 RPM seems appropriate only for cruising on an engine such as that.

I really appreciate the insights. I’ll start downshifting on my uphill climb. It’ll probably drop my mileage from 39 to 35 but with over 200,000 on the engine, I’ll save the engine. Have to remember that at that altitude, I’m already losing 27% power (3% per 1000ft) No need to overwork it.

A 98 isn’t likely to have ‘drive by wire.’ Downshift. If the engine is lugging such that you have to floor it to go 45, you’re not doing it any good. You’re putting extra stress on the bearings and probably generating quite a bit of carbon deposits.

We do a lot of mountain driving and always downshift on those long uphill streches. The engine is more flexible and driveability is improved.

I recently crossed the continental divide in New Mexico west bound and Colorado east bound driving a 2005 Toyota Corolla with automatic. On ascents the transmission was very predictable in keeping engine stress as low as possible based on my demands. And although the GPS fuel calculator is not very accurate it would seem that there was only a 3 mpg loss in mileage from crossing Oklahoma and N Texas compared to the mountains. Of course the speed across Texas was 75+ and in the mountains that was not possible. FWIW, the actual fuel mileage for the 4,000 mile trip was 36.2 mpg and the engine seemed to enjoy 3,200 to 3,500 RPM on steep ascents.

“You can also find comments from engine re-builders who can tell if an engine was lugged by looking at the rod bearings.”

The engine rebuilders are making an assumption. Unless they know the driver and have gone riding with them, they really can’t tell. But I was not talking about lugging an engine, I was talking about loading. The point at which an engine is lugging is based mostly on the cam profile. Many engines operate smoothly under heavy load and low RPM.

Now I have had vehicles that I would not operate under heavy load at 1800 rem or less because they weren’t designed for it. They will lug badly, but I have found many engines are perfectly happy at full throttle at 1800 rpm or less.

“do a little searching for ‘hydrodynamic lubrication’ and you’ll find that low speeds and heavy loads do a double whammy on sleeve bearings.”

You are also making an assumption that I don’t know anything about “hydrodynamic lubrication”.

I would speed up to 51 mph and forget about it. But that isn’t the essential issue . . is it? The question is whether to lug or race the engine. Only you can make that judgment when driving. Flooring the gas pedal would certainly seem to be time to shift, but that’s me. Racing (not really . . . 2300 rpm isn’t bad) isn’t all that bad either . . given your reported range. I would seriously speed up a little to 51so that your engine feels “comfortable”. Rocketman

Just be careful not to get too shifty…you’ll draw attention to yourself.