what type of oil is best?

[Anonymous]

tony i have used the motorcraft semi-syn.[blend] in a 2000 150 and a 2005 150 it seemed ok, but i can't find any data on this oil.the switch to royal purple and a k&n filter gave me nearly 5 mpg on the 2005 150. after seeing the wear tests i am sold on this oil,imho. it is becoming available in more locations and the price seems to be coming down. i am going to use it in my 200 six after break-in on rotella.

 

[rickwrench]

If you run a flat tappet cam, you need to run an oil with high zinc dialkyl dithiophosphate (zddp). Modern oils are formulated for roller cams/lifters, roller rockers, or, OHC engines, not old flat tappet pushrod sixes. Zddp is bad for modern catalytic converters (and their warranties) so it has been reduced to minimum (or nonexistent) levels in the past few years. Just barely enough for roller everything engines, not nearly enough for flat tappet cam engines.
The link below lists most of the current oil formulations available now.

http://www.butler-machinery.com/resources/newoils/

The big jugs of Rotella 15w/40 are a still a good bet for our engines. Motor oil for deisel engined cars is also good, although they are reducing zddp levels there too. Racing oils also have good anti scuff additives. Brand names mean nothing anymore, read the formulas.
Rick(wrench)

 

[jahearne]

What would we look for when looking up oil formulations for high levels of zddp? Would be the P (Phosphorous) and/or Zn (Zinc) content?

 

[rickwrench]

Higher zinc is better for us. Some racing oils are high in molybdenum as well. Which is also good.
It's getting tough to find high zinc oils these days because the API standards have mandated it's reduction for catalytic converter longevity. Some of the best high zinc oils aren't API certified, too high a zddp level. Some of the worst are also not API certified.
There needs to be a "flat tappet" specification that conforms to API standards with higher zddp levels. But it will never happen. So, use 15w/40 Rotella as the minimum standard, and go from there.
Rick(wrench)