Hi guys,

I wanted to put 3 gauges in my dash under the single unit stereo. Water temp and boost gauge were a must. I wasn't sure what should occupy the third spot, so I bought an oil temp gauge. I hooked up the first 2 right away, and wired the oil temp gauge to everything except the yet-to-be-installed sender.

The install went great. Looks like stock. Dimmers work. Lighting matches. Beautiful!!

After some deliberation, and since it's time to change the oil, I have decided to try a drain plug replacement with a sender in it for the oil temp gauge.

So, what's the point?? I want to know what the experts think about differentials in oil and water temps in different scenarios.

Does the oil warm up faster than the water at different boost levels? At idle? How hot is too hot for the oil?

Seems like a good topic for discussion.

Adam

 

Adam,
What gauges did you get? And with the water temp, did you have to install a sending unit or tapped it in somewhere?

 

You usually tap the thermostat housing for the water temp gauge.

 

Your water is going to heat up faster than your oil. I had an oil temp guage but I replaced it with water. Mine was tapped through the drain plug and was kinf of a pain in the *** when it came time to change the oil. If you put it through the drain plugh I would suggest you put a connector on the wire to make it easier to remove the plug. Good luck!

 

Don't use the drain plug. That location will not represent the hottest oil in the system and will also be slow to respond to temp changes. It's expensive, but an oil filter block adapter from Greddy works great. It comes with 2 1/8" NPT threaded outlets for oil temp and pressure.

I am curious as to what most people are getting for oil temps. Feel free to chime in people...

 

For the water temp sender, I bought a greddy aluminum radiator hose adapter(36mm). I had to tap it to work with my sender. I cut out a one inch section of the radiator hose just after it straightens out of the engine. Put in the apapter, and used a couple of hose clamps. This should be the hottest spot for water temps. Of course, it doesn't tell me anything until the thermostat opens at 180. By then my stock gauge has been telling the engine is warm for 2 or 3 minutes.

I bought VDO gauges. The oil temp sender replaces the stock drain plug, and has a spade connection. I am going to give it a try. If I dont like it, I'll probably try the Greddy unit. I have heard that changing the oil filter is more difficult with the Greddy adapter.

My plan is to connect the sender with my current oil: Castrol 20/50. I'll let the car idle until it gets as hot as it is going to get, and check the temp. Then I'll change the oil to Mobil1 15/50, and see if there is a difference.

I'll let you know.

Adam

 

I would definatley go with the greddy block adapter for the oil temp gauge. It can't be that much more of a pain then it already is. Plus you can just pick oup one of those strap rachets from sears, i just picked mine up last week. Haven't had a chance to try it out yet.

 

I have been told that the greddy adapter's thickness lifts the oil filter higher up. Because of this, something else now has to be disconnected to remove the filter. Also, I would have to tap the greddy unit for my sender. I'll try the drain plug sender, and let you know how it goes.

 

low 70's C generally with swings to the low 60s and upper 80's. Water temp around 83-85.

 

thanks David, do you have an R-model or base/pep/touring?

 

I hooked up the oil temp gauge to the drain plug sensor this morning. I did a little test.

It's about 50 degrees. I'm in the garage, doors open and not much of a breeze. I have castrol 20/50 in the car right now. These readings are all taken at idle, starting from a cold engine.

water temp......oil temp
180................150
190................150
200................160
210................170
220................180
225................190
fans on............195

I'm going to allow the car to cool, and change the oil to Mobil one 15/50. I'll do the test again. I'll also do some tests on the road. I'll post the results.

Adam

 

225 seems a little high for your fans to be comin on, may want to check that out...mine kick on at 210 (I think with the parking lights on) And if I leave the key in the ignition in the on position after the car is stopped they come on at 210

 

'93 touring. I have my fans come on full at 85C as well.

 

My gauge may be a little off, plus it is located right at the hot spot where the coolant exits the engine. I wouldn't mind if the fans came on a little sooner.

I did the same test as earlier with mobil one 15/50. Same outside temp. Car cold after sitting for4 hours.

water temp............oil temp
180........................125
190........................140
200........................145
210........................150
220........................160
225........................170
fans on..................170

I took the car out for a spin. After everything settled in, I seemed to be running around 188 water temp, and 220 oil temp. This was easy driving around 55 mph. Next, I thought I would see how things changed with some boost. I ran it up and down the road a couple of times. The water temp gauge went up closer to 200. The oil temp gauge went off the scale. Something hot must have fried the wire connecting the gauge to the sender. Oh well, just a minor problem (that I don't feel like fixing today).

I was really surprised at the resulting differences in oil temperatures from Castrol to Mobil 1. Looks like an average difference of around 20 degrees. I had heard that synthetics ran cooler.

What do you guys think?