What kind of Oil?

Mobil sells a good synthetic, so does Amsoil. 5W40 is the standard for synthetic diesel oil.

 

15w40 is the standard use for diesels during summer months, 10w30 when it gets cold. Cranking over molasses in the winter is never good. For synthetics as freightlinerman said 5w40 is what the standard is. You are correct 5w40 will be thinner when hot than 10w30 but will be thicker when cold. If you are going to run a full synthetic I would recommend mobile over anything. I have never been a huge fan of amsoil for the same price I can buy mobile. I don't think rotella makes a full synthetic and I wouldn't waste the money on that crap anyway. I have always had problems with rotella foaming. My pickup runs 30lbs at cruise and it foams up not impressed. Never have had a problem with mobile foaming.

A heavier oil will increased your oil pressure. And with a thinner oil you WILL find oil leaks. We have run heavier weight oils in vehicles before to solve oil leaking issues. Keep that in mind. I would contact Detroit and make sure you can get by with a 5w40 oil and that clearances and what not will not be effected. Also ask about changing oils given the milage. I have seen what happens when a car yes I'm using a car as an example has been run for 150k with conventional 10w30 and then has been switched to royal purple which is a full synthetic. Was not pretty if they'd been running it from the get go it would've been fine however after running a conventional and switching to a synthetic it doesn't work well. In 30k we ended up tearing the motor down.

 

I politely disagree with 379exhd. You do have it backwards. 10w is thicker than 5w. 10w is usually used as an all-around (all-season) oil. But if you tend to run in colder climes, 5w would suit better. This is from 2 yrs as a mechanic in the Army and 2 college courses.

That all said, we are talking about multi-viscosity oils, hence the xxw30 or w40. As you can see, the 10w30 you mentioned has a more narrow range than the 5w40 freightlinerman suggested. I have always liked 5w40 in my personal vehicles for it's greater range. Stays thinner in the cold so it will continue to lubricate, but thick enuf in the heat so it doesn't just melt away (and continues to lubricate.)

I have only trucked for a yr, and that, as a company man. So I use what they give me, which is usually in a recycled bottle, meaning I have no idea what the brand or weight of the oil contained inside actually is. I was taught that oil pressure anywhere from 20 to 60 psi in my truck is satisfactory. So I like to see it right up the middle, where yours appears to be. On blistering days in the desert SW, I've seen it hovering right at 20. On frozen northern MI morning startups, it will almost reach 100.

My final comment...


I don't care if I'm using my fairy Godmother's own special oil with a magic machine that removes every last contaminant including those NOT known to mankind. I would not leave engine oil in a truck for 100k miles. Your opinion may vary.

 

UGH long day did it again thank you for the correction. Although I will disagree with you're range speaking. Oil clearances are what's going to be important. I could care less about range I want to make sure that the oil is going to be able to maintain the clearances needed during conditions. If the clearances match up during all ranges yes that is fine, if not hell no I'm not running that in my motor.

I'm did not go to school to become a parts changer, didn't need to pay for it learned it in a garage over the years. I have seen what happens when using the wrong oils. Spent 10 hours stripping down a 350 that was dropped in a racecar because they ran 0w10 in it. Sure enough she ran...but not for long. Oil was 2 thin and we ended up with metal on metal contact. When I pull a dipstick and see metal shavings in the oil after less than one night you know there's something wrong. Loaded it on the trailer and headed home. Tore her down and was not impressed. I still to this day blame the oil after a rebuilt royal purple 10-30 went in her and she's ran fine ever since. Never been apart, no shavings, and she's won a few times. This is also why I do not trust or like rotellla that most people seem to swear by. I have seen it foam, in both my cummins and my CAT. I've never seen foaming from mobile unless it has been overfilled, that is not the oil that's the operator many people don't realize what overfilling a motor with oil will do.

As for bypass filters all depends on the filter. Have you ever seen a motor with a gulfcoast on it after 425K and no oil change? I have, they do work, I would trust them. somebody else was the guine pig there not me. I trust it. I would feel fully confident running 500k+ on an oil change with a gulfcoast filter. Other filters eh I don't know gulfcoast has the reputation, I've spoken with Jerry personally he knows what he's talking about, sometimes I think he knows more about what to do than caterpillar as much as I hate to say it. It truely is amazing what a good quality bypass filter will do. I've seen compairible motors and they're gummed up, not with the bypass filter.

 

How many miles on the motor? I realize that you just bought it 15k ago, but how many miles were on it at the time of your purchase? I ask for this reason, mineral oil causes seals and gaskets to swell slightly over time, while synthetic oil causes these mineral oil swollen seals to shrink.... if you have an engine that has, say, 450k-600k mileage on it, and has been lubricated with mineral oil throughout this time..... introducing synthetic oil into this engine is highly likely to cause significant seepage/leaking. Just fyi.

Synthetics are great oils, and if your engine has a history of using mineral oil, and if a full synthetic is going to cause more problems then it's worth, (leaking expensive oil), there is an option for you.... synthetic blends.... something like Mobil Delvac Elite.... you get the long drain capability of the synthetic, and the mineral oil will help keep the seals as they are now, if mineral oil has been the oil of record. It's a win/win... you get oil that has longevity and you prevent excessive leakage.... the other problem with changing over to synthetic in a high mileage mineral oil based engine is the superior cleaning power of the synthetics, they remove varnishes from metals.... this may not be a good thing if your engine has a heavy varnish build up inside it....

Don't fall for the marketing claims made by the oil bypass manufacturers. They are trying to sell you their product, and while bypass systems are great additions to the full flow filters, thinking that you're going to change oil once in a 100k interval is a little unrealistic. When you change out a GCF you are doing a partial change.... you are removing oil from the system, and replacing it with make up, or additional oil. It's called "sweetening", and yes, you can extend the drain interval by this method, but it may not be the money saver you're thinking it to be.... and oil sampling and analysis is going to be extremely important to your maintenance regimen. My advice? Pull a sample right now, have a really good lab analyze and advise, and go from there.... A lot of guys are having Speedco or Sapp Bros do this on site while you wait, but guess what? None of these places can give you a detailed interpretation of the results and advise you concerning the OCI, (oil change interval), and, at any rate, oils break down over time due to oxidation and shearing.... That being said, I run synthetic and do extended drains.... I have a Detroit, 600k on it now, I change oil at 60k intervals, I monitor with UOA's and I have a dual bypass setup. I also use Donaldson Endurance full flow filters. Does my UOA indicate that I could go longer on my OCI? Yes.... but, do I really want to push my equipment to the maximum interval? No. Why? Because at 60k I've accomplished my goals, namely, I've maximized my OCI relative to the cost of doing a complete drain and change.... If someone was sponsoring me and was going to finance the cost of a new engine should the need arise due to pushing the envelope on the oil change interval, then I would entertain the idea of really finding out just how far one could extend this interval.... (and 60k really is the reasonable limit for my engine, oil, and filtration system as at that mileage the oil is beginning to break down and become volatile)

Yes, you should stick with the OEM's recommendations while beginning an oil analysis routine and go from there....

Or, you could just follow the OEM's recommendations and probably never have an issue due to experimenting with your engine. Only you can make this decision.

Just remember, a new motor will cost some money.

 

As far as brands go, I personally think the Mobil Delvac line is the best one going for class 8 truck motors. The regular old Delvac that you can buy at Walmart for like $10 a gallon is really, really a good oil....

You could probably use that oil, change at 30k intervals per the OEM schedule, use a pair of quality full flow filters, like the Donaldson's and go 1.5 million miles no problem...

The bypass setup won't reduce the wear rates significantly, I don't believe, but they will allow you to extend the change interval. The way to think of it is economically, will bypass, synth oil, and extended drains save me money over regular mineral oil and traditional truck maintenance approaches?

Will I gain MPG with a synthetic? (yes, about one to two tenths of a MPG)

Do I get improved pump-ability and cold start ease in the wintertime with synth oil? (yes)

Do the additional costs merit the change over to synthetic?

Is there something else, (semi synth blends), that could be a better option?

It's a lot to think about, that's for sure.

I don't know if I helped, but my intention is to help.

Congratulations on purchasing your new baby, I know you want to maintain it with the best of everything..... I can relate.

 

I'm coming from the world of diesel pickups so take this fwiw.

The biggest reason I run synthetic is for cold starts. Yeah, lots of motors get good long life in MN winters just by plugging them in overnight, but I like NOT hearing that awful "diesel rattle" in sub zero temps.

I have run Amsoil 15w-40 (yeah it's synth), Amsoil 5w-40, Mobil 1 5w-40, Shafers 9000 full synth 5w-40 (not the blend crap), and maybe a change or two of Rotella. Everything except the Rotella was sampled and none had any real advantage over the others. Never did any kind of scientific study, just that nothing stood out good or bad. Although the one time I put 16K on Amsoil 5w-30 the analysis said it could have gone further. 16K in a pickup was long enough for me.

In a situation where something goes wrong and your engine gets hot REALLY quick, you should get a little more protection using synthetic. The higher coking(?) point keeps the oil as oil to a higher temp. Could save an engine. Pretty slim odds that a situation like that occurs, but if it does, you have a little better chance of just needing to change oil instead of changing engines.

A ranking of the synths I've used based on nothing more than personal preference

Shafers 9000---A good oil that doesn't cost near what amsoil or mobil do. In 55gal barrel it's give or take $20/gal. compared to $35-$40. Yes the 9000 is FULL synth, not a blend. If not for the price factor, I'd be running Amsoil or Mobil.
Amsoil---in a little cold test we did here with ams, mobil synth and conventional, and rotella, the Ams ran off the stick the best at -10*F. The mobil synth was almost as thick as the conventional. Didn't have shafers at the time.
Mobil---Never had any bad experience with it, it's just really expensive and shows no benefit over the others.
Rotella---Too cheap. Not sure it's really a FULL synth.

Blends are a complete and total waste of money. Everything I've heard tells me they're all right around 10% synth, 90% dino. And...you can make your own if you want to. No reason you can't blend synth and dino when you change.

If long life is what you're after, just taking the time to read my babblings tells me you care enough about your engine that you're most likely gonna get a good long life outtta her regardless of what oil you use.

 

I have grown partial to Schaeffer brand of oils. http://www.schaefferoil.com

I can get the Series 9000 5w40 full synthetic (a group III and group IV combination) for less than $20 a gallon, delivered free to me, and free oil sample kits included. I just priced a drum yesterday..... $1080 for a 55 drum, 3% off special, and free deliver to me or my dealer will have it shipped to him and he will bring it to me.... free. Even Wally World can't top that deal. And Schaeffer has been making great lube products longer than any other oil company in America... since 1839. Mobil, Shell, everyone else joined the party later.

The Schaeffer 7000, a synthetic blend 15w40 is $130 a drum cheaper than the 9000 series. Same free delivery. The 7000 has 25% PAO synthetic with group II+ conventional.