270 Dipstick Readings

[Jim 123]

This one has left me scratching my head and I'd be interested to learn if other 270 Owners have the same observations.

My car runs has the standard, wet sump, 1.6 Ti VCT engine. As per the handbook, if I check my dipstick with the engine reading "hot" i.e. after a run, having left my car for 10 minutes. The oil level reads maximum.  If I repeat the dipstick reading after the car has sat overnight and the engine is totally cold, the reading is halfway between maximum and minimum.

I've put this phenomenon down to a small amount of hot oil expansion; as well as a possibility that some oil is "backing up" into the dipstick tube whilst the engine is warm and cooling down. (The latter point is a speculative guess on my part).

I'm going to err on the side of safety and top up the oil based on "cold" dipstick readings, but I'd appreciate it if anyone with a similar configuration has seen the same.

[Dave J]

oil expands and that is why you should correct the level when hot as per the handbook. 

[Jonathan Kay]

Wouldn't you have to take into account the thermal expansion of the metal container as well?

Jonathan

[Jim 123]

Thanks both,

I'm intrigued about the large expansion relate difference I am seeing on my car's dipstick.  I wasn't expecting to see quite so much relative to the volume of oil in the sump, and I hadn't thought about metal expansion in the alloy sump pan.  On my Sigma it looks like the bottom of the dipstick enters the sump at an angle as opposed to sitting vertically into the oil, and this will also exacerbate the hot / cold dipstick readings that I have seen.  

Wikipedia and a calculator to do some thermal expansion estimates may satisfy my curiosity.

[Garry R]

I have a 270 (now upgraded to a 310) and I was very worried when I first checked the oil (cold). I couldn't get a proper reading at all, but when I checked it hot, as per manual, it was right on the max, so no problem.