Oil changes with synthetic

lots of opinions out here so Ill throw mine in, well not realy an opinion, but with my old truck a 1999 f250 7.3 diesel I put a bypass filter on it and did an oil analisis program to determin how long my oil would last. it lasted
80000km/50000 miles before its base depleted to a point where I should change it. I settled on a change interval of 50000km which is 35k ish miles to give me a buffer. saying that a oil doesnt wear out unless it is overheater is just untrue. yes that will acellerat it, but the base is what wears out usaly long before the other properties of an oil and the more humid it is and the more stop and go trafich and short interval run times the faster it will wear out as it is what nutralizes the acidity that is creadted by the gunk your oil keeps in suspension and moisture to keep it basic. if you do oil analisis and you base is low you can just add more base. old truckers used to do this all the time with out knowing it by adding gallon of oil to there rig every week to top up the leaks. in a normal vehicle I always recomend that you go by the owners manual as they cannot deny use warenty if you do that so they must figure it is a reasonable interval. if you modify your filtration system you can go longer but you have to pay for oil programs to determan how far then you should do one every now and then to determin if you have any issues going on. my self I go by the ford factory oil minder but I use the extream duity oil.

Steve

Amsoil had documented hundreds of thousands of miles logged on semis running their oil, changing nothing but the filters. Everyone can argue about how long oil should be changed, but without using real data from a lab, and not just algorithms, personal preference and superstition your just guessing. If you have the oil lab checked, you can know for sure.

dodge guy wrote:

Groover wrote:
The bottom line is that oil will essentially last forever unless it gets contaminated or overheated. I sincerely doubt that he is overheating it. The main source of contamination is cold starts that allow more blowby of unburned fuel and exhaust gases which contain carbon and water. The problem is compounded if you don't get the engine hot enough to boil out the water. If the car sits in a garage without being driven the oil will last a very long time. Just watch the short trips and temperature cycling.

I have noticed that time spent on a dealer lot does not seem to count towards oil changes. At least that is what the dealer told me when I bought a truck that had been on the lot for 7 months.

Oil is contaminated on the first start. It also gets heated all the time. Doesn’t need to get overheated to fail. Even run at proper temp oil still breaks down!

I take it you have the documentation to back up that statement? Personally I think it's nonsense. I have mine checked at every oil change, and contaminants are always extremely low: fuel less than .5%, antifreeze and water 0, Insolubles .3%. Granted those are at 5,000 mile intervals.

Groover wrote:
I have noticed that time spent on a dealer lot does not seem to count towards oil changes. At least that is what the dealer told me when I bought a truck that had been on the lot for 7 months.

I bet resetting the OLM is part of the new vehicle prep. That is a reset without changing the oil.

Groover wrote:
The bottom line is that oil will essentially last forever unless it gets contaminated or overheated. I sincerely doubt that he is overheating it. The main source of contamination is cold starts that allow more blowby of unburned fuel and exhaust gases which contain carbon and water. The problem is compounded if you don't get the engine hot enough to boil out the water. If the car sits in a garage without being driven the oil will last a very long time. Just watch the short trips and temperature cycling.

I have noticed that time spent on a dealer lot does not seem to count towards oil changes. At least that is what the dealer told me when I bought a truck that had been on the lot for 7 months.

Oil is contaminated on the first start. It also gets heated all the time. Doesn’t need to get overheated to fail. Even run at proper temp oil still breaks down!

The bottom line is that oil will essentially last forever unless it gets contaminated or overheated. I sincerely doubt that he is overheating it. The main source of contamination is cold starts that allow more blowby of unburned fuel and exhaust gases which contain carbon and water. The problem is compounded if you don't get the engine hot enough to boil out the water. If the car sits in a garage without being driven the oil will last a very long time. Just watch the short trips and temperature cycling.

I have noticed that time spent on a dealer lot does not seem to count towards oil changes. At least that is what the dealer told me when I bought a truck that had been on the lot for 7 months.

JIMNLIN wrote:

Cummins12V98 wrote:

time2roll wrote:

Cummins12V98 wrote:
Never heard of 80% rule.

Ratings are always under the actual capabilities with a builtin margin.

1/2 ton = rating x 80%
3/4+ = rating / 80% ;)

So by me running at my SAE RAWR of 9,750# I am overloaded?

Maybe some documentation on this 80% rule.

Its a rv thing from the era when our trucks had wimpy 180-235 hp v-8 engines and inline 6 cylinder engines and 1 1/2"-1 3/4" wide front and rear brake shoes....hot running slusha' automatic tranny with no TC lockup...small radiators/etc Probably a good idea....back then.

Todays LDTs ??
We use them in commercial service up to 100 percent capacity and make it fine for 250k-300k +/- miles before major repairs pop up. Works for rv trailers also. These trucks sure aren't like 1970-80 versions.

Thanks!

dodge guy wrote:

Cummins12V98 wrote:

dodge guy wrote:
Here is another way of thinking about it!

Why is it when it comes to tow ratings most people say to never push the ratings and to only go 80%! Yet when it comes to maint most people want to push the interval to at or farther than what the manuf recommends.

Just curious!

Never heard of 80% rule.

Ratings are always under the actual capabilities with a builtin margin.

I know that, you know that, but there are many people that don’t understand that.

Guess so!

Grit dog wrote:

Cummins12V98 wrote:
"No way could I go a full year without an oil change. I just couldn't do it."


The oil Companies love you.

His bank account probably still loves him too, since he's rolling a 250k+ mile (I think) truck. He's saved more money than many of us put together and the peace of mind of doing something that may keep a high mile engine ticking 1, 2 or 5 years longer is worth far more than an extra $50/year in oil.

The one thing that can kill a Chevy LS engine is the small passage on the hydraulic lifters can clog up and the lifter will no longer function. Keep your OCI reasonable and that Chevy engine will last a loooong time.

Cummins12V98 wrote:

time2roll wrote:

Cummins12V98 wrote:
Never heard of 80% rule.

Ratings are always under the actual capabilities with a builtin margin.

1/2 ton = rating x 80%
3/4+ = rating / 80% ;)

So by me running at my SAE RAWR of 9,750# I am overloaded?

Maybe some documentation on this 80% rule.

Its a rv thing from the era when our trucks had wimpy 180-235 hp v-8 engines and inline 6 cylinder engines and 1 1/2"-1 3/4" wide front and rear brake shoes....hot running slusha' automatic tranny with no TC lockup...small radiators/etc Probably a good idea....back then.

Todays LDTs ??
We use them in commercial service up to 100 percent capacity and make it fine for 250k-300k +/- miles before major repairs pop up. Works for rv trailers also. These trucks sure aren't like 1970-80 versions.