Debate: New way to figure oil change interval

[Posm]

I have been thinking of a way to adjust for the many different driving styles that I do within a particular oil change interval. I somtimes run empty for several thousand miles and then I may pull a very heavy load for a thousand miles. I do not believe that either miles or hours gives a good indication of the amount of "work" that my truck has done during a period of time. I have come up with a plan to keep track of the number of gallons of fuel that I put through between oil changes and change every 400 gallons of fuel. This would adjust the intraval up when I run at a constant 60 MPH and get 22 MPG and adjust it down for extensive idle time as well as hard 10 MPG pulling. I know that oil samples would help establish a "perfect" change interval if I did the same job with my truck all the time. However, like many others, my truck may do very diffrent jobs at a moments notice. I am sure that my theory has some holes in it so flame away.

 

[RustyJC]

I believe Caterpillar uses this system as the basis for scheduling maintenance for some of its stationary industrial engines based on the premise that the amount of fuel used is somewhat proportional to the number of brake horsepower hours produced.



Rusty

 

[JJW_ND]

Based on lots of oil samples from my 96 5sp, I can tell you hard pulling is much easier on the oil then intown driving. Any use that gets the engine up to normal temps and keeps it their for a long time (this includes WOT for hours on end) will allow one to extend oil drains.



It is the short trips in cold temps that can short drain intervals. I have take all samples at 6K mile intervals. I know I had some intervals that consumed 500 gallons of fuel. Even though these were in the dead of winter they were some of the best samples. I have never had a oil sample come back recomending changing the oil. I have run Premium Blue 2000, Amsoil 15W40 and now Amsoil 5W30. I dumped the PB2000 at 6K anyway and I dump the Amsoils at 25K (every 25K has checked out OK also). No Bypass filtration, just Fleetguard filters.



jjw

ND

 

[klenger]

I think your system makes sense. Since some of the contamination is from the burned fuel, the more fuel you consume, the more contamination there would be. I don't think your intention is to find a perfect method, just adjust the interval for different uses. Makes alot of sense to me.

 

[15w40]

My BMW has an oil change indicator in the dash. It counts down by monitoring how long the engine has run, the engine RPM, and the oil temperature. I don't know the exact algorithm they use but at higher RPM and temperature, it counts down faster. These parameters would be difficult to keep track of in our Rams, but I agree with the other posts that keeping track of fuel usage is better than mileage.

 

[TwoSlick]

Posm,



I came up with the same idea some time back ... .



If you do short trip driving in cold weather, your fuel efficiency will be terrible, so you are compensating for this with the fuel burn idea. I also think that you should take into account the sump capacity. For passenger cars & trucks I came up with this formula, (when using a 11-12 TBN synthetic):



Gas engine:



Change oil when fuel burn = (500 gallons)(sump capacity in quarts/4 quarts)



Diesel engine:



Change oil when fuel burn = (250 gallons)(sump capacity in quarts/4 quarts)



So for the Cummins you would change oil when you have burned approx 750 gallons of fuel. At an average fuel consumption of 15 mpg, this would be equal to approx 12,000 miles. This is conservative based on the oil analysis results I've seen to date.



TS

 

[pwr2tow]

need reply from JJW-ND

JJW-ND,



I was thinking of switching to synthetic delo 400 5-40 and I have a question for you.



1. I see you are running 5-30, are you going to use it all year or just in the winter.

2. Are the oil samples from useing 5-30.

3. Do you tow heavy when useing 5-30.



I like the idea of running one oil year around verses 15-40 in summer and 10-30 in winter. Switching to one oil will save me money by eliminating haveing to dump oil early because seasons and temperatures change and I plan on extending oil drains from 3,000 miles with mineral base to 6,000 miles with synthetic.



I would have sent you a PM but I thought it would be good information for anybody else that is considering synthetic.



Thanks, Ron

 

[JHansen]

Not just Cat stationary engines!

Don't know if they still do-but the amount of fuel consumed was Cat's recommended way of determining service time for truck engines too-at least the last time I looked. Not just for oil changes-for everything up to and including inframes. Thinking of going this way myself down the road here-I know the 5000 km (around 3000 mile) changes I do are gross overkill-but I'd rather err on the side of caution especially with the type of driving I do.



Jason

 

[JJW_ND]

5W30 Year round!

Ron:



I have ran Amsoil's Series 3000 5W30 the last 60K miles. That is ten samples on that oil. As compared to the previous 140K miles and oil sampling it has out performed anything I have run.



"Towing heavy... " Up until this year, I average about a trip a month to KS pulling new stock trailers back. Always least doubles, sometimes three or a stack of three tandom duel flatbeds. You catch a lot of wind with 60' of trailer behind you. How many miles nonstop have you ever had your truck WOT... 1,10, 100!



The worst samples are always from the interval with the fewest pulls, most short trips and WINTER. Some of the best samples were from intervals that contained those WOT pulls for 100s of miles. Last December I as on the last 6K of a 24K interval. Probably one of the longest 6K intervals timewise since I had the truck. Record cold december. Was the hardest I can think of on the oil. Oil already had 19K on it. For the first time I was able to get the percent soot higher then the minimum value of . 1 with a value of . 2. TBN was still almost 10. Even though I dumped it was still fine to continue use as was EVERY sample I have ever tested. Here is some more reading if you want... https://www.turbodieselregister.com/forums/showthread.php?s=&threadid=16993&highlight=5w30



Other then the high cost, this is the best oil for year round use for those of us that have to deal with sub zero temps. The difference going to 5w30 full synthetic from 15W40 full synthetic was much more noticable that from the semisynthetic 15W40 to full 15W40. Very quick oil presure, much easier cranking and faster starting. I don't even worry about plugging in done to -10. With the Premium Blue 2000, I need a boost at -15 when not plugged in.



A good 5W synthetic can handle the heat as good as it handles the cold! It is the cold starts the hurt not the WOT summer heat!



jjw

ND

 

[pwr2tow]

JJW-ND,



Thanks for the reply and some very good information. The information has calmed my nerves about useing a 5 weight oil year around. I tend to error on the side of caution too much and usually try to find as much information as possible before I do anything. Thanks again for putting my mind at ease.



Ron