I’ve read that short stops are bad for the oil condition because the oil does not heat up enough to burn off the water (byproduct of combustion).
What about multiple short stops (15-20min rest in between…say 5 stops)? From one stop to the other, the coolant temperature reaches 207 degrees…enough to turn on the radiator fans. Isn’t that more than enough to remove the water from the oil?
How much running time is there relative to resting time? If the crankcase vents are free flowing and the engine is operated at cruising speed for a significant part of the day moisture would not likely be a problem.
+1 to Rod Knox’s comment.
The length of the stops is not as important as the drive time from home to the first stop, from the first stop to the second stop, etc.
It runs 15-30 minutes between each resting time (reaches speeds of 40-50mph…some bumper to bumper). However, the very first stop is only 10 minute drive (with 20min rest).
I change my oil + filter every 3000 miles, so it doesn’t matter…but just wanted to know.
Coolant at 207 deg does not mean that the oil is at 207. The oil will cool faster than the coolant because the oil is better exposed to the air in the oil pan.
It takes a fairly long run at higher city speeds to boil off the water. When the oil on the dipstick is milky light brown it is time for an oil change.
If, as you say, some of your hops are as long as 30 minutes at up to 50 mph I’d say you have absolutely nothing to worry about.
“When the oil on the dipstick is milky light brown it is time for an oil change.”
In that case it’s overdue for a change or there’s a problem (head gasket, etc.)
If there’s enough moisture to change the appearance of the oil on the dipstick “Houston, we have a problem”.
Milky goop on the underside of the fill cap is an early warning sign.
I understand your concerns. If it’ll make you feel better, Next time you have your engine oil changed, Have them up in Synthetic oil that’s PAO and not type III. PAO will no mix with water (moisture).
If there is moisture in the engine it will usually show up under the oil fill cap and in the dipstick tube as a milky sludge.
The scenario you describe is fine in normal climates. Water is a normal product of combustion, and unless the engine reaches full operating temperature the water in the combustion gasses that blow by the rings (all engines have some level of blowby) can condense on the cooler metal surfaces and run down into the oil pool in the oil pan. If the engine is at full operating temperature, the metal surfaces are warm enough to prevent condensation and the gasses in the crankcase are warm enough to retain the water vapor and carry it through the Positive Crankcase Ventilation (PCV) system up to the space under the valvecover to be reingested into the engine.
The reason I mentioned the climate is that when I lived in North Dakota we had a terrible time in the winter even getting our engines up to operating temperature. We had to plug the cars in overnight (engine heaters) and put cardboard or blankets over the radiators. Even then it takes a while if the car’s been sitting all night at -40F. If you live in such an extreme condition, it’s a good idea to let the engine warm up some before taking off (not recommended in more normal climates). If you live in such a climate, it’s also a good practice to change your oil more often than the owners’ manual recommends.