My VDO oil temp gauge is connected to a VDO sender in the sump
Reads accurately to within a degree as have tested it with boiling water
Since replacing the oil cooler and tightening the tin ware up my engine (a stock) 1600 runs at 90degrees on a cruise and upto 100 when climbing long hills - before changing the oil cooler it was hitting 100 and 110 respectively
However without getting hung up on temps it is more important to know what is normal for your bus/engine and monitor that for any adverse changes
Reads accurately to within a degree as have tested it with boiling water
Since replacing the oil cooler and tightening the tin ware up my engine (a stock) 1600 runs at 90degrees on a cruise and upto 100 when climbing long hills - before changing the oil cooler it was hitting 100 and 110 respectively
However without getting hung up on temps it is more important to know what is normal for your bus/engine and monitor that for any adverse changes