Gunk in the oil dipstick tube

[Rattnalle]

Taking an extra hours drive each week just to boil the oil off doesn't make sense compared to just shortening the OCI a bit. Factor in wear on tyres, fuel etc and it just doesn't make sense.

And the obvious: walk or ride a bike if it's so short the car doesn't even get warm. Cheaper and healthier for both car and driver.

[June]

Taking an extra hours drive each week just to boil the oil off doesn't make sense compared to just shortening the OCI a bit. Factor in wear on tyres, fuel etc and it just doesn't make sense.

And the obvious: walk or ride a bike if it's so short the car doesn't even get warm. Cheaper and healthier for both car and driver.

This makes 100% sense to me. I thought 6K oci on a short trip driven car has to be bad for engine longevity. June

[Rattnalle]

Taking an extra hours drive each week just to boil the oil off doesn't make sense compared to just shortening the OCI a bit. Factor in wear on tyres, fuel etc and it just doesn't make sense.

And the obvious: walk or ride a bike if it's so short the car doesn't even get warm. Cheaper and healthier for both car and driver.

This makes 100% sense to me. I thought 6K oci on a short trip driven car has to be bad for engine longevity. June

Factory OCIs, 20000km in my case, are always specified for "beneficial conditions". That is long trips att moderate speed in a temperate climate. They never specify how much shorter they should be for other conditions though..

[misha]

Shorter oil change interval will not prevent oil condensation and milky dipstick from frequent short trips in cold weather....the fact is that it can appear in a few days after oil change....and vanish the same day after longer driving.

[June]

Shorter oil change interval will not prevent oil condensation and milky dipstick from frequent short trips in cold weather....the fact is that it can appear in a few days after oil change....and vanish the same day after longer driving.

I was thinking more of fuel dilution of the oil and the length of time it would take to put 6K miles on a car that primarily ran short trips would have to be a recipe for wear and sludge? June

[Rattnalle]

Shorter oil change interval will not prevent oil condensation and milky dipstick from frequent short trips in cold weather....the fact is that it can appear in a few days after oil change....and vanish the same day after longer driving.

The issue to care about is water and fuel buildup in the oil though. Not cosmetic condensation in the dipstick tube. Sure it might be an issue for the pcv too but as long as the car does some longer trips it'll be fine.

[abscate]

Taking an extra hours drive each week just to boil the oil off doesn't make sense compared to just shortening the OCI a bit. Factor in wear on tyres, fuel etc and it just doesn't make sense.

And the obvious: walk or ride a bike if it's so short the car doesn't even get warm. Cheaper and healthier for both car and driver.

I never considered the economics of this but you are absolutely right of course.

One extra 20 mile trip per week is 1000 miles per year, or something like $200 in cost for a depreciated car.

[Rattnalle]

Taking an extra hours drive each week just to boil the oil off doesn't make sense compared to just shortening the OCI a bit. Factor in wear on tyres, fuel etc and it just doesn't make sense.

And the obvious: walk or ride a bike if it's so short the car doesn't even get warm. Cheaper and healthier for both car and driver.

I never considered the economics of this but you are absolutely right of course.

One extra 20 mile trip per week is 1000 miles per year, or something like $200 in cost for a depreciated car.

Over here 1000 miles is about $200 in fuel alone. Plus the other stuff. While one oil change with 5w40 and filter is closer to $30.

[Sommerfeldt]

Yup... driving a whole heap of tiny trips with horrendous fuel economy, a cold engine and water in your oil and then changing that oil more often makes a whole lot more sense. [/sarcasm]

- S

[Dave in Maine]

I'd like to thank all who contributed their advice. A couple points:
1. The 6000 miles oil change interval was on synthetic. On non.synthetic I had limited my interval to 3000 miles or less. The 5600 miles I drove on that oil change included about 3500 or 4000 miles of high-speed highway driving, including a pretty-much-nonstop trip from Detroit MI to Portland Maine (~900 mi), two round trips from Portland to NYC plus a couple weeks of highway commuting in the NYC area (375 mi one way, plus daily commutes of 30 mi one way on the Jersey Turnpike), and various highway driving around home. If I feather the gas pedal correctly, my trip computer tells me I'm getting 24-26 mpg on extended highway cruising at 70 mph. Yes, there is a lot of in-town driving recently, too.
2. I had the PCV valve (and tuneup) done about 3000 mi ago. Seemed like it was time, since I'd driven the car about 70k since acquiring it and hadn't had either done. PCV had about 50% varnish; plugs may have been original. Mileage went up by about 4-5 mpg highway immediately.
3. It has been cold here the last couple weeks. It is 6F (-15C) here this morning. (Yes, it starts right up, first try.) I would not be surprised if there was a lot of condensation going on.
4. I will discuss with my mechanic having him do the combustion gas test on the radiator. As noted above, it seems cheap insurance.
5. Walks are good. But at 6F the only reason I'd be taking them is to walk the dog, and I no longer have a dog.
I'll keep you posted how this turns out.
Thanks again!