Originally Posted By: roadrunner1
They dont spec 15w-40 in the 6.7 period, manufacturers are moving away from 15w-40 for economy reasons.
How so? If you are a biofuel user, which in most metro areas of the US you have no choice, they "specify" to use either 5W-40 or 15W-40 (see #2 below the graph). Here from the owner's manual diesel supplement:
Originally Posted By: roadrunner1
Your original question was" what temp is too hot for conventional", you haven't even come within 150f of the flash point.
I would contend that long before reaching the flashpoint (which the lowest temperature at which a liquid will generate sufficient vapor to flash (ignite) when exposed to a source of ignition, or fire.) the oil will be cooked, coked, done. How would the oil perform at 260F for sustained operation? Still viable? My concern is that at a sustained temperature of 240°F and above the oil will begin to breakdown.
I just completed my 3,900 mile trip (which was 100°F-117°F for at least 1,500 miles) and the highest oil temperature I saw (unloaded) was 249°F. Would that be the maximum I would see since you state the oil cooler would be fully open at 245°F? Without towing under the same conditions I would cannot say, but I would not be using a conventional oil at that point. Below is Ford's definition of severe service. I meet one of those requirements daily (use of biofuels--although I do not see that as "true" severe service) but since operation above 100°F is another, I for one am quite satisfied that I had a synthetic 5W-40 in the sump.
Originally Posted By: roadrunner1
The CJ-4 spec is not an easy spec to meet and with CK-4 rolling out this fall it will be even tougher to comply with.
Curiously enough, it seems that oxidation from high heat is one of the issues addressed with CK-4--which sounds like would be the oil for the conditions in which I just operated. I also wonder if CK-4 will need to be a SynBlend in order to pass the tests?
Here from
Chevron (I only added the oxidation part):
Originally Posted By: Chevron
Traits of Superior Performance
The common thread between FA-4 and CK-4 oils is that both will deliver superior performance over the current CJ-4 category, especially when it comes to new challenges for equipment users. When considering your PC-11 oil purchases, three of the most important traits to look for are:
Oxidation stability
Wear protection
Piston deposits
Oxidation Stability
Performance tests for the new category of oils reflect the industry’s focus on meeting the new challenges users face. Along with seven stringent tests used for current oils, the new oils also must pass two additional, very demanding tests. In particular, the aggressive Volvo T-13 test addresses oxidation, or oil’s propensity to break down at high operating temperatures. Oxidation is especially harmful to engines because it causes oil to thicken and form deposits, and it fosters corrosion. Oxidation stability in the new PC-11 oils is intended to address those issues. It is also a key factor allowing OEMs to consider extending recommended oil drain intervals. In fact, Chevron recently added an oxidation indicator to its recommendations for used oil analysis. Finding an oil that can maximize protection against oxidation will be crucial.
At any rate, RoadRunner, I appreciate your thoughts as well as everyone's answers and dialogue--good thoughts and points from all!