Big John, Welcome to the FTE
Hard to say whether or not your 7.3 PSD would respond any differently to synthetic or not... You might want to post this question in the Diesel 7.3 forum. I can say that a lot of folks run synthetic in their diesels and swear by it while others think it's a waste of good $. I prefer Mobil1 5W40 synthetic in my 6.0 PSD although I've heard that you really want to stick with a 15W40 in the 7.3 regardless of whether it's conventional or synthetic- And there's only a few synthetics available in 15W40.

 

In my 7.3 going from a syn (Rotella T6) to Mobil delo 400 dino the engine runs much quieter at idle, the diesel mac at the local Ford garage told me Ford does not recommend syn in the 7.3, other then that there was no difference in how it operated.

 

How long (time)/ miles can I, should I go with dino oil verses syn oil, heard I could go 12000- 15000 per oil change. ???. I am also thinking of putting dual oil filters in a remote location, will this affect the life of the oil???

 

No way I would go that many miles on ANY oil without having an oil analysis done every 3-5000 miles!! If the engine is still under warranty even if you do have analysis done it wouldn't be covered.

 

Looking at SAE J300, the oil viscosity spec, at 150C SAE 40 does not equal SAE 40. 5W-40 has a High Temperature High Shear viscosity max of 2.9 cPs. 15W-40s HTHS viscosity max is 3.7 cPs.

 

Why not it is an SM, SL, SJ..etc rated motor oil. It will run just fine in a gas engine.

Agreed!
Why stick with a 15w-40...even Ford makes a 10w-30 for cold weather? Most HDEO 10w-30 are far more shear resistant than 15w-40 or 5w-40s.

Ford makes their own 5w40 synthetic so that is just wrong. But unless it gets below 20* where you live I doubt you will ever see a difference between synthetic, a blend or conventional oil in a 7.3 with a properly functioning set of GPs

 

If you've been using conventional oil, it is way too late to switch to synthetic. You probably have all manner of little scratches and gouges in combustion chambers that are currently being kept sealed through conventional oil build-up. The synthetic will flush all that out, and all of a sudden you might discover your losing compression. Especially at 300k+ miles. My rule of thumb has always been keep feeding it what you started it on, unless you get a full rebuild.

 

When did gasoline engines start requiring SN oils? I own a 2004 F250 gas engine and a 2010 Escape. There are a couple of quarts of Citgo 5w20SM semi synthetic in my garage. I'd like to use them when one of my vehicles gets a quart low.

 

I believe it was Oct 2010. Your '04 doesn't require API SN, ILSAC GF-5. Look in your 2010 Escape manual, to see if it says to use API SN, ILSAC GF-5.

 

I bought my Escape in December 2009. I'll be able to use those two quarts in either of my vehicles when I need to add a quart.

 

A Ford guy I know says you can use a diesel rated oil in an older car, but if it's a late model car or pickup with emission controls (cats - 02 sensor ect.) it's not a good idea. He's replaced numerous cats, 02 sensors and all needless due to the formula of a desel oil - it's additives are specific for diesels, ash content ect. That's all I needed to know.

 

Greenhead,

Thats some great mileage on the dino. I would probably just stick to what you have been doing since it worked so well. I have about 291k on a 351w and I figured I'd stay with dino since thats what got it there.

 

Remember post 2008 diesels have o2 sensors and cats and DPFs oh my! So most Cj-4 diesel oils are sm and sl rated, so you can run them in many gas engines.

A note on synthetics and longevity, a former employer of mine had an e150 with 528k on the original engine and second trans. A few years ago and still over 400k miles on it they started using super tech synthetic to help with winter starts...and ran conventional in the summer. The van works on a college campus with a ton of low speed use and cold starts, so brutal operating conditions and I drove by about a year ago and they are still using it.