I bought this oil pan heater, well... just because I like gadgets and it's cheap.

http://www.northerntool.com/webapp/w...9139_200339139

I installed it yesterday and tried it out this morning. I have it stuck on the side of my oil pan (as the bottom is ridged) and the plug hooked to the bottom of the drivers side running board so it's easy to plug in. I have it plugged into a timer so it's only on about a couple hours before I leave in the morning, it gets the oil pan really hot, pretty impressive for 150 watts. It only got down to 38* F but still my truck started up like it was already warmed up and the engine warmed up much faster. They say most wear occurs at cold startup maybe this will help. Probably completely unnecessary but figure can't hurt.

 

What grade of oil do you use. If you use 10/40 you are starting the engine with 40 weight oil. And can cause a spun bearing.

Most block heaters heat the water in the block.

 

I noticed it is 150 watts, and while that doesn't seem like much, we made a heater that would heat lunch with a 100 watt light bulb. You may be boiling your oil and there is no saftey or thermostat. I would be careful with that, and not recommend anyone else do it..

 

Yes exactly the point. Not trying to be mean but If you are saying 5w-40 oil is thinner at 30* F than at say 150* F I think you need to read up a bit on how oil works. I can give you some links if you want to read up. Here is a good start, the author touches on most everything:

http://www.carbibles.com/engineoil_bible.html

These heaters are made for certain size oil pans btw. Mine is for an under 8 quart oil pan and it it not going to scorch the oil or anything. It does not get that hot when compared to the oil temp at operating conditions.

 

When you see a W on a viscosity rating it means that this oil viscosity has been tested at a Colder temperature. The numbers without the W are all tested at 210° F or 100° C which is considered an approximation of engine operating temperature. In other words, a SAE 30 motor oil is the same viscosity as a 10w-30 or 5W-30 at 210° (100° C). The difference is when the viscosity is tested at a much colder temperature. For example, a 5W-30 motor oil performs like a SAE 5 motor oil would perform at the cold temperature specified, but still has the SAE 30 viscosity at 210° F (100° C) which is engine operating temperature. This allows the engine to get quick oil flow when it is started cold verses dry running until lubricant either warms up sufficiently or is finally forced through the engine oil system. The advantages of a low W viscosity number is obvious. The quicker the oil flows cold, the less dry running. Less dry running means much less engine wear.

 

I only see one problem with that though, the oil temp is alot hotter than the coolant temp.
So while a cars engine runs in the 200*F range the oil gets much hotter than that, the temps inside a crank case can easily reach 400+*F.
Towing a trailer, off roading, anything that really works a engine, and that is why/when you get engine sludge and oil burn off.
The oil gets to hot and it breaks down.
While a higher viscosity is less likely to break down it still happens.
Every body needs to evaluate their oil needs and use a type/weight of oil that is right for them.
My truck sits out side so in the winter I use a 5w-30, but in the summer when I am off roading in 95*F summer temps with the a/c on and the fam in the truck climbing hills, driving in deep sand, towing the utility trailer, etc I use 15w-50.
I think that for the average person a 5w-40 or a 10w-40 is a good all around choice.

 

it would be easy to throw a thermometer on the oil pan and see just how hot it gets.

i really doubt the heater would get hot enough to affect the motor oil.