Yes, I use these type infrared thermometers in my job. I'm a Facilities Mechanic. We use them to check a/c and heating units and sometimes circuit breaker panels for loose high resistance wiring problems. They work, but IMO not totally accurate.
It would be interesting to compare readings to one with a sensor submerged in fluid inside the pan vs outside surface temp.
There would be very little effort to add a bung to the pan since it will be off for replacing the filter.
I've spoken to the manufactures of the product Scangauge ll which plugs into your OBD port. Sounds like the 2006 and later cars can use Scangauge. I asked this question, because I own a Scangauge ll
Below is our email ....
Question to Scangauge:
I own a Scan Gauge ll. To service the transmission in my Chrysler Crossfire SRT6, I need to know the transmission temp to set the proper fluid level.
I read some where, this can be done with a ScanGauge.
Is this true and if so, how do I accomplish this?
Thanks in advance.
Steve
Answer from Scangauge:
Stephen,

Unfortunately, we only have transmission temperature available for 2006 and newer Dodge/Chrysler/Jeep vehicles. This is due to the protocol the vehicles use. Until 2005 Dodge/Chrysler/Jeep vehicles used ISO or VPW, then in 2006 they started switching to CANSF. The transmission temperature we have only applies to vehicles that use the CANSF protocol and unfortunately, your vehicle uses the ISO protocol. If you have any questions, please let me know.

Regards,

Cristina Bollinger
Repairs and Technical Support
Linear Logic
1.888.433.5664