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Oil issue for the newer 6.7 Diesel

F-250 / Super Duty / Diesel

Oil issue for the newer 6.7 Diesel

Old 12-04-2017, 01:04 AM
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Join Date: Mar 2003
Location: So. Texas
Posts: 1,992
Oil issue for the newer 6.7 Diesel

Don't know how many of you have gotten the message about the oil issues and the 6.7 concerning the newer CK rated oils. In basics, you can't use them and that's going to be a problem. There is some major confusion in regards to what this is about. Ford in their 1000 hour testing found that there was excessive wear especially at the valve fulcrums using the newer CK rated oils. They are now recommending that you do not use them. The CK rated oils are formulated for better fuel efficiency via lower viscosity. The goal with the new trend in diesel oils is just like it was with the gas engines, thinner oils make better gas mileage. They're pretty much wanting to drop the Xw-40 oils and implement 10w-30 oils, then 5w-30 oils, then 5w-20 oils for your diesel engines. Obviously, these oils are NOT going to be backward compatible with older diesel engines. So until this is decided on by Ford and probably ILSAC, you need to make sure the oil you buy is the old CJ rated oils. Using the newer CK oils will cause damage to your engine. There are all kinds of commentary online about using specific oils and there's a supposed list on the net but Fords position as of now is that Motorcraft 10w-30 oil or Rotella T6 5w-40 oil ONLY is approved for use in your engine. If you can still find the old CJ rated oils, the oil is still good for use in the 6.7. If you have any of the earlier Ford diesel engines, CJ oil ONLY, which may become hard to find but make sure of what you are buying. Look for the API Starburst and the CJ rating. Here's Fords statement of fact on the issue:

In formulation, the issue is the reduced amount of viscosity but more important is the reduction of phosphorus in the mix. Phosphorus acts like a cushion in formulation. It has been reduced to API SN standards which means a maximum of 800 ppms. That's about a 50% reduction. This is where the excessive wear is coming from.
Old 12-06-2017, 02:56 PM
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Join Date: Mar 2001
Location: Rochester, NY, USA
Posts: 3,226
Hmmm, very interesting. Unfortunately, the average consumer isn't as well versed as Labnerd and that's going to cause problems - which will probably lead to premature engine failure for those that didn't heed this warning. That kind of sucks. By thank you Labnerd for educating those of us here.

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