I've been running Mobil1 full synthetic since I've owned my truck (62k miles now), I noticed some threads on Motorcraft Syn Blend and my Wal-Mart carries it and the MC filters, so I thought about switching.

Is there any harm to switching from a full syn to a syn blend? I've heard some say that once you go full syn, that you shouldn't use a conventional oil again.

 

Old wives tale in my opinion. MC oil should do just fine. DO use MC filters - they were designed for your engine.

- Jack

 

10-4. Thanks for the quick response.

 

Ran full synthetic in my 2008 from new until about 60k. Switched to the motorcraft blend for the same reason you are. I'm at about 100k miles and haven't had any problems. Doesn't use a drop of oil.

 

Good to hear! Thanks!

 

THis is an old issue that went away back in the 90's. The issue was that synthetics of the day had no seal swell agents in them. You had to have the engine broke in and the seals taken care of by the conventional oils first. There were a ton of leaks before the formulators figured out that the synthetic MUST have a seal swell agent. The Gp IV and Gp III base oils do nothing for seals.

You can change back and forth all you like today. Most all of the Gp IV base oils are gone due to rising costs of the ethylene gas used to make them. Some will use an ultra high viscosity index Gp IV to trim the oil spec and call it a synthetic. Most any base oil these days with the exception of the solvent refined Gp I base oils are now considered a synthetic. Frankly, the word synthetic is pretty much useless info when it comes to motor oils. Many have pushed the envelop with the Advertising Councils definition of synthetic. By their definition, if it does not appear in nature, it is a synthetic. A Gp II oil does not appear in nature. So a lot of yesterdays conventionals now wearing a synthetic name. For any engine today, the best way to judge any oil is to look at the ASTM 5800 testing. That is a test for the oils evaporation rate over 1 hour at 482F represented in a percentage of weight lost. The maximum is 15% per API. The lower the number, the better. This is especially true of any turbo engine and the EB engines. The lower number reflects an oils stability due to heat. A non-turboed engine may not necessarily need such a stable oil as they do not run the internal temps of a turbo engine. Cookoff/evapration may not be an issue for a naturally aspirated engine. Generally, if it wears the Ford certification, it's a pretty tough oil.
http://www.pqiamerica.com/samplesummaryPCMOrev4test.htm

 

As always great lubrication information Labnerd.
Thanks.