Cummins ISX CM871 Technical discussion

50-PSI seems a bit high for that engine. Sounds like too much Lucas in it or something.

I guess its time to bash on Lucas a bit here (hopefully it will not start an argument). First some personal background: 18 years working with and around hydraulics in the automation sector prior to trucking taught me very well, that a $25,000 precision high speed Linear Actuator will start to fail as soon as the additive package in the oil drops off, long before any dis-coloration sets in. I used to work with customers and oil suppliers directly concerning oil additives, viscosities, pressures, etc. but still consider myself an amateur because it is a vast ongoing science that I do not have time to keep up with.

that being said, this is what I have come to know (I have dug deep into oils for my engine)...

Lucas is to oil, as Stop-leak is to coolant. Lucas is an ultra-purified non-synthetic 110 straight grade oil combined with 20-30% 'Olefin copolymers', and nothing more. It itself has no real engine protecting 'Addative Package' to protect your engine. Olefin copolymers only serve to restrict oil flow (like the sawdust seen in radiator stop leak products), and at 20+% its quite good at it. Its an oil thickener, nothing more and for every gallon you put in your engine you are thinning the other oil's additive package by roughly 12%. This means 12% less lifespan (educated guessing, roughly 1.7% more wear above the engine oils current wear rating, growing exponentially with every gallon) for your oil for every gallon you stuck in for those components that require a high volume of oil flow.

So what does this translate to in an ISX?,...

The ISX seems to be a high-flow, low pressure lubricated engine. Restricting the flow will increase pressure (as seen on the guage) and change the wear-rate of everything in the engine. The Oil sampling i have done to my own engine was not as good with lucas, and I found out that the bottom half of the LF9080 oil filter will gum up with the polymers in lucas, shortening its effective life. This is what I saw on my own truck, but others may have different results. It will definitely slow down how fast your engine burns oil, but it is almost always cheaper just to burn the oil. $36 bucks for 1 gal lucas, where it MIGHT make your engine burn 1-1.5 gallon less oil. HMMM,... 1 gal oil = $12-13 vs $34-36 for gal lucas. 1 gal lucas = cost of 3 galons of oil. Just burn the oil. That's the energy of one less gallon of fuel you had to buy to move your truck as well, so the oil is only costing you $12 - $3.80 or $8.20/gallon for the 2 or 3 gallons you had to use. More oil than that, get your engine rebuilt. The DPF on your truck will build up with ash at a higher rate, but all of the modern oils are now CJ-4 compliant, witch reduces this effect greatly. So instead of ashing at 700k, maybe you get ashing at 550-600k miles.

Thicker oil in the ISX lowers fuel mileage slightly, but does however provide some benefits to certain components. Thicker oil is well known to lower turbo shaft temps, especially in hot weather. Its also better for the gears in the front of the motor as well as the overhead cams when the engine is running slightly hot. Is lucas the solution to this?,...No, because there are many types of oil that can be used for 'Thickening' purposes that actually DO have additive packages in them. A half gallon to gallon of good 75/90 non-synthetic gear lube is one of them. Just choose one that has a low ash rating if your engine burns oil also.

Delo-400 oil, something I wrote a while back. Could explain your consumption as well...

The brand of oil you use in your engine is actually very important. Unfortunately, advertising, opinion, truckers stories, price, and ten thousand other non-factual, non-scientific, senseless reasons, is how most people, and unfortunately, most mechanics, choose their brand of oil. This is actually perfectly ok to do as long as you stick with the top, most popular brands. They all work well, and they all will protect your engine. So why is the brand very important? The biggest reason, is that it is actually harmful to change brands. What happens when you change brands of oil, is that the wear patterns on all the components that need oil in your engine will change. This causes accelerated wear to your engine until the new patterns set in. Also, because these patterns change, your engine will use oil at a higher rate until it settles in again. It is enough of a change that your engine could suddenly need a gallon of oil every 5,000 miles, where before, it didn't need any at all. After maybe 40,000 miles, the new patterns will set in and your engine should stop using oil so much, going back to the way it was. My point here, is that you have just signed the lease to a truck, so whatever brand you choose, you should stick with it.

If you are actually not sure, then perhaps some education will help. The HFRR rating of an oil is its rating on how well it protects metal parts as they rub together tightly. CJ-4 (you see this on the bottom of the label), is a compliance rating that has to do with the amount of ash that is left behind after the oil is burnt, and Zinc, is an additive in oil that coats parts to keep them from touching each other when there is very low pressure available. There are many more ratings and compounds, but these three are very distinct, when comparing oils in a scientific manner. The top 3, most common brands of oil you see at truck stops is Delo 400, Mobil Delvac, and Shell Rotella. All have a good ash rating at about 1.3-1.35%. The ash rating is important because, if it is too high, and your truck has a DPF, then it will eventually get clogged with ash and have to be removed for cleaning, as ash cannot be burned off. Rotella-T is the only oil of these with Zinc. This gives it better protection than the other oils on engines with low oil pressure like a Cummins, but the Anti-wear (HFRR) rating is not so good (1.20). Of the other two, Delo has a far superior Anti-wear (HFRR) rating at 0.04, and Delvac is listed at 0.25, and both of these oils are designed to protect engines with higher oil pressures like Detroit, Cat, and Mercedes. It seems clear, when looking at just the science behind these oils, that in fact, the (usually cheaper) Delo-400 is in fact a better oil on higher pressure engines, and that Rotella-T is better for lower pressure engines. Other Non-synthetic oils that you typically see in truck stops, such as Kendall, Valvoline, etc. fall short compared to these 3. Hopefully, this bit of technical info will open your eyes a bit when it comes to choosing an oil. To further research this, just look up 'Bob The Oil Guy' on the web, and you will see.