Adventures with dipstick warmer - PeachParts Mercedes-Benz Forum

strelnik · #1 02-17-2015, 04:04 PM

I committed the terrible sin of leaving summer oil inside the 190D when the temp hit -4 Fahrenheit. It was molasses.

Charging the battery and heating the block does not help when the oil is this thick. The heat does not transfer to the pan and the oil.

I borrowed a dipstick heater that was 24" long and checked it in its place in the 190D/ 601 pan. It went inside almost 5 inches.

The heaters always say to use all night but I have heard stories of cars in Canada burning due to oil fires from dipstick heaters.

So I left the heater in place for 30 minutes, watching the car from inside and drinking coffee.

After 30 minutes, I unplugged the heater and VIOLA! the car turned over like July! I let it warm up thoroughly while I prepared everything needed for an oil chantge.

I did it in stages becauise of the weather but it didn't take long. Left the belly pan off for now, it goes back on later after I wash it.

MY QUESTION: What are your experiences with dipstick heaters? Good bad? Use 30 minutes? Use less?

I have ordered a two foot tall glass test tube ad will heat several litres of oil from zero degrees to whatever, checking and recording the temp with a laser thermometer every minute from 0-15 minutes.

That should help decide if it's a good idea.

My only other concern is that the heater may overheat the oil, sizzle it too quick. So the poil will be used oil. Hope that does not impace results.

Any comments based on experiences with dipstick heaters?

connerm · #2 02-17-2015, 05:17 PM

My comment is that the volume of oil in a test tube is vastly different than the volume in an oil pan and keep in mind the massive amount of metal surrounding the oil in the sump.

connerm · #3 02-17-2015, 05:27 PM

I have used the heaters that you insert in the lower radiator hose. They worked on my Caprice's 305 and my Rabbit's engine when I lived in Illinois.

Zacharias · #4 02-17-2015, 05:52 PM

You were lucky. Around here dipstick heaters are regarded as an absolute last resort to be used in situations like that (but I have never heard of such great results, especially in such a short time).

To the other poster, lower rad hose heaters have been discussed on this forum and the consensus is that they don't do much on these motors because of the design of the thermostat. All you end up heating is the coolant in the hose and a bit of the rad, but with the Tstat closed that is as far as it gets... the heater isn't hot enough to open the Tstat.

In areas that rarely see cold weather, they would be a more cost effective option than installing a block heater, but in Michigan and Quebec, not really useful.

97 SL320 · #5 02-17-2015, 10:00 PM

How many watts is the dipstick heater? ( 200W maybe? ) The issue is they have a limited surface area so heat transfer is slow.

I've vote for a magnetic stick on heater with a thermostat.

Diesel911 · #6 02-17-2015, 11:47 PM

There is various types of heater that attach to the exterior of the Oil Pan like the Magnetic one mentioned. Not all are magnetic,
They are likely to heat slower but at the same time I think are less likey to burn the Oil

tjts1 · #7 02-18-2015, 12:23 AM

Not sure magnetic heater is going to be of much use on an aluminum oil pan.

Zacharias · #8 02-18-2015, 01:01 AM

The upper section of the oil pan on an OM617 is aluminum. The lower is not.

I have used magnetic heaters before. They are better than nothing but I would guess less than half as effective as a block heater.

They warm the oil but nothing else. In very cold temps, the starting difference is really evident.

I would imagine a glued-on heating pad would be roughly the same?

strelnik · #9 02-18-2015, 11:02 AM

Quote:

Originally Posted by Zacharias

The upper section of the oil pan on an OM617 is aluminum. The lower is not.

I have used magnetic heaters before. They are better than nothing but I would guess less than half as effective as a block heater.

They warm the oil but nothing else. In very cold temps, the starting difference is really evident.

I would imagine a glued-on heating pad would be roughly the same?

The issue for me is that the heat in the block (from a block heater) does not transfer significantly to the oil pan and the oil.

So if you don't change your oil on time, that oil must be somehow heated to reduce strain and speed up the movement of the crank+pistons that create heat-compression.

Besides, it's cool to own a 24" x 4" diameter test tube!

funola · #10 02-18-2015, 11:41 AM

Instead of measuring how long it takes to heat up the oil in your test tube, measure the surface temperature of the heater. My guess is 700 to 900 F. Use the dipstick heater to get the engine started to change the oil but don't make a habit of using it as a substitute for a block heater before consulting with engine oil manufacturers whether that kind of temps speed up the degradation of the oil.

strelnik · #11 02-18-2015, 11:46 AM

Quote:

Originally Posted by funola

Instead of measuring how long it takes to heat up the oil in your test tube, measure the surface temperature of the heater. My guess is 700 to 900 F. Use the dipstick heater to get the engine started to change the oil but don't make a habit of using it as a substitute for a block heater before consulting with engine oil manufacturers whether that kind of temps speed up the degradation of the oil.

My reason for conducting this experiment is EXACTLY what you said.

If the diprstick heater warms the oil to 700 degrees, the oil will be burned and useless!

My idea was to verify the temp of the dipstick heater, then find one that never heats above 250 degrees Fahrenheit. This ensures that the oil, if heated 100% to that temp (which I doubt) would NOT be burned, that most water condensing would be steamed away, and that the oil would flow.

This is why I only used the dipstick heater for 30 minutes. Heating the oil enough to start the car, so I could change the oil, was my goal.

funola · #12 02-18-2015, 11:57 AM

Quote:

Originally Posted by strelnik

My reason for conducting this experiment is EXACTLY what you said.

If the diprstick heater warms the oil to 700 degrees, the oil will be burned and useless!

My idea was to verify the temp of the dipstick heater, then find one that never heats above 250 degrees Fahrenheit. This ensures that the oil, if heated 100% to that temp (which I doubt) would NOT be burned, that most water condensing would be steamed away, and that the oil would flow.

This is why I only used the dipstick heater for 30 minutes. Heating the oil enough to start the car, so I could change the oil, was my goal.

No need to do the test tube test. If the temp of the heater surface is 700 to 900 F, you can be sure the oil that is in immediate contact with that surface is also 700 to 900 F. With convection, more and more of the oil in the sump will be in contact with the heater. A magnetic heater will not have that problem since the the heat is more spread out compared to a dipstick heater and the pan adds another layer to decrease the heat density.

strelnik · #13 02-18-2015, 03:35 PM

Quote:

Originally Posted by funola

No need to do the test tube test. If the temp of the heater surface is 700 to 900 F, you can be sure the oil that is in immediate contact with that surface is also 700 to 900 F. With convection, more and more of the oil in the sump will be in contact with the heater. A magnetic heater will not have that problem since the the heat is more spread out compared to a dipstick heater and the pan adds another layer to decrease the heat density.

The thing is-- I don't know that the tip of the dipstick heater is 700 degrees, 900 degrees or 300 degrees!

I can heat it up and use a non-contact thermometer to see, as with a glow plug.

My point is: I am doing an experiement because everyone here on this forum is guessing as to what the temperature is, no one knows or has come forward with documentation to tell me.

If I had that, then I would stop and use the data.

I have no data as yet, just OPINIONS.

97 SL320 · #14 02-18-2015, 09:43 PM

There may be a limitation to running the stick heater in free air. ( as in it might burn out / overheat .) Oil offers a heat conducting medium that will lower the surface temp of the heater.

Zacharias · #15 02-19-2015, 12:08 AM

Quote:

Originally Posted by strelnik

The issue for me is that the heat in the block (from a block heater) does not transfer significantly to the oil pan and the oil.

How do you conclude that?

I have on two different OM617s had the situation where the block heater died and I had to use a magnetic heater on the oil pan for a while.

In both cases, there was a evident difference in cranking speed between using the magnetic heater and having the block heater.