Oil temperature question

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Jim Beam
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Oil temperature question

#1 Post by Jim Beam » Thu Nov 14, 2019 7:48 pm

1963B(T6) Base car. I believe that my OEM oil temp gauge reading is inaccurately high. (Broken original temp sender - long story). Drives me crazy to see the temp gauge needle approaching the red zone. I use a Precision Matters dipstick thermometer to measure oil temp at the sump. I understand the sump oil temp to be the hottest point in the oil system. Question is: If I am running an oil temp of around 220/240 degrees F at the sump (as per the dipstick thermometer), is my oil temp OK or do I have an oil temp problem which needs to be addressed? Thanks for the wisdom.

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Ron LaDow
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Re: Oil temperature question

#2 Post by Ron LaDow » Thu Nov 14, 2019 8:40 pm

Jim,
Just saw your email to Precision Matters.
You don't want dino-oil running much above 250*, but you prefer it above 212* to boil off the water.
Ron LaDow
www.precisionmatters.biz

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C J Murray
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Re: Oil temperature question

#3 Post by C J Murray » Thu Nov 14, 2019 9:31 pm

Oil temp goes up and down depending on load but I wouldn't worry about your readings.
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Re: Oil temperature question

#4 Post by Mike Horton » Fri Nov 15, 2019 12:46 am

Jim, you can test the accuracy, at a single point, by extending the wires, and let the temp sender probe, sit in a pan of boiling water, under the car, at around 212*F, that should get you close enough, to confirm your ga. reading... Ron's temps, are correct.
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Re: Oil temperature question

#5 Post by Tim Berardelli » Sat Nov 16, 2019 7:04 pm

Jim,

Difference in oil temp. between sump temp. and what comes out of the cooler is about 50 degrees-you are fine!

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Don Gale
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Re: Oil temperature question

#6 Post by Don Gale » Sat Nov 16, 2019 10:01 pm

Mike Horton wrote:
Fri Nov 15, 2019 12:46 am
Jim, you can test the accuracy, at a single point, by extending the wires, and let the temp sender probe, sit in a pan of boiling water, under the car, at around 212*F, that should get you close enough, to confirm your ga. reading... Ron's temps, are correct.
Good idea! except boiling point of water in Albuquerque is approx. 200F (5500 ft elev +/-). Don't let the probe touch the bottom of the pan.
1958 356A 1600 Super Sunroof Coupe
former 1966 Euro 912 Sunroof
former 1978 Intermeccanica Speedster w/'68 912

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Re: Oil temperature question

#7 Post by Mike Horton » Sun Nov 17, 2019 12:43 am

Don Gale wrote:
Sat Nov 16, 2019 10:01 pm
Mike Horton wrote:
Fri Nov 15, 2019 12:46 am
Jim, you can test the accuracy, at a single point, by extending the wires, and let the temp sender probe, sit in a pan of boiling water, under the car, at around 212*F, that should get you close enough, to confirm your ga. reading... Ron's temps, are correct.
Good idea! except boiling point of water in Albuquerque is approx. 200F (5500 ft elev +/-). Don't let the probe touch the bottom of the pan.
Oh, Don, did I forget to write at sea level, standard day conditions?

Oh, yea', I did say" around 212*F"... common sense, & judgment required. I always suspected you Alb. guys were high,
Mike

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Re: Oil temperature question

#8 Post by Mike Horton » Sun Nov 17, 2019 12:46 am

IIRC, there is a vintage article somewhere on Wilhoit's site, from "around '58", about this very subject,

Ron, Cliff, Tim, +1
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Re: Oil temperature question

#9 Post by Mike Horton » Sun Nov 17, 2019 1:09 am

Mike Horton wrote:
Sun Nov 17, 2019 12:46 am
IIRC, there is a vintage article somewhere on Wilhoit's site, from "around '58", about this very subject,

Ron, Cliff, Tim, +1
… Don, +1... (he, he, he)
Mike

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Don Gale
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Re: Oil temperature question

#10 Post by Don Gale » Sun Nov 17, 2019 10:08 am

Mike Horton wrote:
Sun Nov 17, 2019 12:43 am
. . . I always suspected you Alb. guys were high
That would be our neighbors to the north of us.

Years ago, I calibrated the coolant temp gauge in my BMW by tie-wrapping the temp sender to a known accurate digital meat thermometer and submersed them in mineral oil on a hot plate, gradually heating them up. The mid-point mark at 182F ordinarily would be when the 176F thermostat opens, so perhaps the data is shifted 5-6 degrees or so:

http://www.nmia.com/~dgnrg/tempgage.htm
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Re: Oil temperature question

#11 Post by Jim Beam » Sun Nov 17, 2019 8:03 pm

Thanks for the responses. "Are we clear? … Crystal." (Nathan R. Jessup from 'A Few Good Men'). Oil sump temperature is about 50 +/- degrees hotter than oil exiting the oil cooler, at which point the oil temperature sensor (sender) unit is located. Therefore, if I have an oil sump temperature of, say 250 degrees, I am probably at 200 degrees or so at the oil temperature sensor (sender) and there is no problem. :D Of course, this is variable and depends upon the load being placed on the motor. Thanks again.

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Re: Oil temperature question

#12 Post by David Jones » Sun Nov 17, 2019 9:16 pm

The quick and easy way to check temps on our cars is to use an IR temp gun available for upwards of $10 from Walmart and Amazon to high end pro versions. Not available back when our cars were made but to me an indispensable tool now. Takes moments to use and are as accurate as our needs are likely to be. Check sump oil temp and temp sensor and know where it is in seconds. It is however recommended that the car be parked and the handbrake on when using, just like a cell phone.
If I had known I would live this long I would have pushed the envelope a little harder.
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Al Zim
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Re: Oil temperature question

#13 Post by Al Zim » Mon Nov 18, 2019 11:56 am

Drive your car down thee toad at speed for 15 minutes. Stop and open the deck lid. Spit or dribble water on the engine case. If the water boils then your temperature is above 212 degrees. The water will probably not boil. al zim I am thinking about how many million VW's did not have oil temperature gauges...all of them. If you are pushing a VW Bus down the road with an upright fan motor (last used in 1971) you are going to make more heat than is possible than driving your 356 normally (less than 75 mph) With an aluminum case engine (356A from 1955) your durability increases. Study your shop manual
carefully carefully as you assemble your engine other not so knowledgeable people have been there before you. al zim
Last edited by Al Zim on Sat Dec 14, 2019 3:22 pm, edited 1 time in total.
 

Jim Beam
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Re: Oil temperature question

#14 Post by Jim Beam » Fri Dec 13, 2019 6:19 pm

Ran a little test. Not under load, just in the garage. Ran the car until the sump oil temp was at 180 degrees, as per both PM dipstick gauge and aux VDO gauge reading from the sump plate mounted sensor. Took an oil temp reading at the stock sensor with a thermal laser thermometer = 152 degrees. At those numbers the original temp gauge in the dash cluster was reading with the needle pointing to 11 o'clock. I think I am good so long as the sump temp reading generally stays at or below about 240 +/-. Thanks for your responses.

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