Cold starting motor vehicle?

Question

High revving engines on highways like high flow thinner oils but low revving highly loaded engines e.g. trucks like thicker oils due to the bearing loadings.

When I start my car the oil is thicker than it should be for my engine, with the above statement in mind would it therefore be better to keep the revs low and labour the engine more, as the thicker oil would protect the bearings better than the cams due to inadequate flow.

Answer 1

No, you would want the oil to flow at its maximum rate with a cold engine to gain full lubrication as fast as possible. Due to the engine not turning at all the oil has "drain" back to the pan and there is a slight time frame that the engine is running with no oil at start-up. Oil pump will run with the engine and provide lubrication faster with low viscosity, a heavier oil would prolong this time and damage the engine more. Depending on the reference you use 50% to 75% of engine wear occurs at start-up.
Diesel gasoline is a thicker substance than regular and does provide a sligthly better lubrication factor in truck engines. The oil pump on these trucks are also run independantly from the crankshaft and therefore provide lubrication at start-up for these type vehicles.

Answer 2

I think just try to start the motor as close to normal rev's as possible and not worry to much about the wear on start up.

If it's a hard starting car you might have to try a time or two more or rev it up a bit more.

For protection I think a blended synthetic oil might be better than a thicker oil unless you have a heavy duty truck with a big motor, like a diesel or something. Also if you are worried about engine wear, letting the vehicle warm up for a minute or two before you pull out should help.

If you live in a cold climate you might let it warm up for longer than the 1-2 minutes.

Answer 3

Running an engine rich will heat it faster.

If you are trying to warm up a car or truck, put a load on the engine by driving in a high gear. This will allow more gas and less air into the engine when its under load. A lower gear allows for more revolutions and sucks more cold air into the engine. This is not good for mpg. Oil viscosity changes with temperature.

Answer 4

In a perfect world, in cold weather, we would start our engines and let them idle until the engine reaches its normal operating temp before driving off and taking to the freeway.

Actually, our engines would do better if we always waited until the engines were at their normal operating temp before taking to the freeway, even in the summer.

This is even more important as an engine ages and the internal oil passages start getting restricted by sludge, making it more difficult to get sufficient oil circulation to all the parts that require lubrication.

Answer 5

Shouldn't you be using a multi-viscosity oil?

It's an interesting theory, but I think there are some tradeoffs with oil pump speed and cold lubrication. Just a guess, but I'd say stay in the middle, don't over-rev, don't lug.

Answer 6

That's why they make multi-weight motor oil, like 10W-30, 10W-40, 5W-30, etc. It has both high and low viscosity oils mixed together, that are good for cold starts, but also stay relatively viscous (thick) at high speeds.

I use 5W-30 for my vehicle.

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Answer 7

If you use the proper grade of oil for the car, as specified in the owner's manual, it makes no difference how the car is driven.

Answer 8

probably be a bad install