When to replace motor?

Personally.....I would be looking into at least doing a inframe, if not a complete overhaul at 1.2 mill.
If you have a trusted mechanic who works reasonably priced in your area then the cost would be alot cheaper then breaking down with a blown motor 1,000 miles from home.
Preventive maintenance is more then just doing oil changes. If I know a altenator has alot of miles on it, I replace it, same with a starter and other mechanical parts. Being proactive can save you money in the long haul by keeping problems down while on the road making money. Plus all these repairs are done while you are on home time so no real lost days from working your truck.

 

Made a similar comment that was responded to with....

"if it ain't broke, don't fix it"


I'm on the road to haul freight, not sit in a motel with a broke truck.

 

Bender got it right. Truth be told, there is NO pure synthetic oil on the market. Mobil 1, Amsoil, Royal Purple, etc all have some form of Group II, Group III, or Group IV base oil combination. Each group brings certain characteristics to the game that are desired. A group IV, while excellent for controlling "burn off" volatility and a very low pour point, also is not the best at keeping the additive package in suspension. So... there is also some Group III or Group II in the mix to take care of that. And the difference in quality between these groups are getting tighter all the time. A group II is your standard Rotella, Delvac, etc off the shelf. A group III is a severely hydrocracked/refined group II and can be labeled a synthetic (i.e Rotella, Valvoline, Castrol synthetics). A group IV is made from natural gas and is more accurately called a synthetic (i.e. Delvac 1, Amsoil, Royal Purple synthetics).

And name brand is really not that important. Most all the labeled brands get their base oil from a couple of producers. The cost difference between them has more to do with advertising, truck show sponsorships, race car sponsorships, etc. I can get a very good synthetic blend at my local farm and home store for easily 30% or more less than the big name brands. And it performs as good or better, based on oil sampling and engine longevity, than any of the big name brands.

Synthetics are good. It is the only thing I will put in my transmission and differentials. I like a synthetic grease as well. But I have not experienced any real benefit of using a high ticket synthetic in any engine... my commercial truck, my Jeep Liberty Diesel, my New Holland ag tractor, etc But, I do like a synthetic blend. It gives me the best of both worlds at a very reasonable cost. Currently, I can get a very good synthetic blend for $13 a gallon. Can't even get a standard mineral oil off the shelf at a truck stop for that low of price!

Got 1.4 mil out of my last engine without opening it up. Sold it and the next owner ran it for quite a while before doing anything to it. Got 7 mpg when I sold it. My current engine is at 847,000 and still has excellent oil samples like it did when it was at 300,000 miles. All on that low priced synthetic blend available at the farm and home store! I concur with others... if the samples still look good, and it is performing right, then the "if it aint broke, then don't fix it" rule applies. But each person has to follow their gut on this. If a person feels that the engine is getting tired and needs an overhaul, then bank for it, plan a time to shut her down, and do it. There is no hard and fast rule here. Plan it right and combine a vacation at the same time so you can kill two birds with one stone. Enjoy some time off doing something you wanted to do, and come back to a rebuilt engine ready to go to work.

 

Knock on wood, I've never sat in a motel with a broken truck, not my truck.. When it comes to starters, water pumps, or alternators I pretty much live by those words and think it's foolish to throw money away replacing them if they're not broken.. I've had issues with those and other things in the past hundreds of miles from home and either fixed it myself on the road or made it back home to fix later no problem. Everybody has their own way of doing it..

 

A couple things that I wouldn't wait until they fail would be the fan hub and the turbo. They can cause major chaos when they come apart and take out other very expensive components in the process. A failure of one of these two on the road can cost you a small fortune.

 

Is your operation local or even regional ? If so than the " if it ain't broke " rule is tough to go wrong with.
If you're OTR and possibly thousands of miles from your preferred shop at any given moment than regular oil samples and closely watching oil consumption will be your best indicators.
If you aren't burning a gallon every 3 thousand miles and your UOA doesn't show anything abnormal you should continue to save your $ and leave yourself in the best possible position when the time comes.