Oil change based on time interval

[dryfly]

I have an Dodge 2005 CTD that has the 7500 mile oil change interval based on towing/heavy use. Since 90% of my truck usage is towing and I only put about 5000 miles on it per year, I usually just change the oil once a year using Rotella T 15w40.

This year I've only put about 2500 miles on the truck. I drive it to the store about once every 2 weeks, getting it up to operating temperature, to keep the battery charged and the seals lubed.

Am I correct in assuming that the oil still needs to be changed at the 1 year mark regardless of the low mileage? I have always been under the impression oil breaks down after time.

Forgive me if this question has been answered 100 times on this forum.

 

[Johnny]

to BITOG

I would not go longer than a year, regardless of mileage. Nasty things build up inside an internal combustion engine.

 

[opus1]

+1.

In the manual for my Cobalt, GM recommends changing the oil based on the monitor, but not going past one year between changes no matter what the OLM says.

 

[Jim Allen]

With today's stellar oils, I've begun to think the one year interval has a lot of safety factor in it. Ultimately, it depends a great deal on the driving cycle, I think. I'm experimenting with 2 year intervals now on two diesel farm tractors, and 1 year + (about 18 months) on a gas car and pickup, as well as a diesel pickup. Will verify with used oil analysis.

I know it takes about 10 miles of steady 55-60 mph driving for the oil in my late model Ford gas truck to reach operating temp (as measured in the oil pan) on a 65 degree day. That's the point where the clock starts as far as cooking out moisture, fuel dilution, etc., goe and think that's fairly typical. How long that cooking process will take to clear the oil would be highly variable according to what's in it. Were you to drive the prerequisite amount, I don't think you'd have a great deal of buildup over a long period. But oxidation would still be occurring. That's where the oil and it's additive package will count.

I submit to you that your truck has a high oil capacity, good fuel metering and you are likely using ULSD. Assuming a quality oil and filter, you are pretty safe. Walking in your shoes, I wouldn't be afraid to stretch out past a year if I subjected the truck to evenly spaced, long and sweaty workouts over the course of the year. But that's me. The safe bet if you are in ignorance of the details is the annual change.

 

[Ken2]

I feel OK with a two year interval. I've run lots of industrial diesels where we've gone 3 or 4 years with good analysis reports. Do look at the oil on the dip stick and into the oil fill cap if you can see anything. Anything that doesn't look good indicates a problem, or at least the need to change the oil.

If your trips were short and cool, I'd change the oil sooner. If your trips are a half-hour or more after reaching operating temperature, that's really good. Just getting the coolant up to temp and not much more does not get the oil fully warmed.

 

[Tornado Red]

Originally Posted By: Ken2
If your trips were short and cool, I'd change the oil sooner. If your trips are a half-hour or more after reaching operating temperature, that's really good. Just getting the coolant up to temp and not much more does not get the oil fully warmed.

I agree with this reasoning.