Ok the search button apparently doesn't want anything to do with oil changes.

Just bought my X a couple weeks ago, I notice that after sitting for a day if I start it I get a puff of smoke but then it goes right away. Previous owner says he puts full synthetic 5w20 oil in it. Is that a good oil for my 6.8 v10 with 115k miles on it? Im about to do my first oil change on it and was wondering if I should change what type oil is in it.

PS. There's also no cat converter in it, that wouldn't be causing the initial puff of smoke would it? Prev owner took it out.

 

Pretty sure 5w20 is recommended for the modular engines. Early 2000's were listed as needing 5w30 but since then Ford recommends 5w20.

Early 2000 4.6/5.4/6.8 engines are known to burn a bit of oil. My 1999 Crown Vic and this 2000 Excursion I have both lose a tiny bit. I'm assuming valve guides.

My last oil change was done with Mobile 1 0w20 full synthetic by PO. Not trying to hijack but is that bad oil?

 

If there is no catalytic converter on it then the PO indeed removed it and might not have adjusted the computer accordingly. I know firsthand from living the Mustang world for 10+ years that screwing with the emissions often causes a zillion little gremlins. Not having a cat (should be multiple cats on a V10) can screw up the A/F ratio and you might be running rich and not know it. This could cause buildup in the exhaust that gets blown out when you start it.

Also, go check your gauge cluster when you start the vehicle, the check engine light should come on when you first turn the key and then go out (unless it is already tripped). If it does not then the P/O might have pulled the bulb which I have seen shysters do before. One of the first things I check for when looking at a used vehicle. If everything is kosher still then pull codes and see if you get anything. You might get a bank lean/rich or whatever that didn't trip the CEL for whatever reason.

Personally though, I would have walked away if I looked under the truck and saw no emissions equipment. Lord knows what else the PO messed with...

 

Mine will do that! if I start it, move it to the street, turn it off then later I go out and start it to move it back in, it will puff a blue cloud of smoke. it is unburned fuel! at least for me anyway. is that the same scenario as you?

 

Yep sounds the same

 

"blue cloud of smoke" = oil - not fuel. It could be from the PVC valve or valve seals. My does the same thing occasionally. Nothing to get excited about.

 

Could be burned oil or fuel in excessive amounts. Unburned is unburned and they both can cause smoke when burned. Mine doesn't do that but I wouldn't worry about it unless you have bad gas mileage or it burns a lot of oil which would indicate that it is continuing after start-up. Burned oil in an overly rich situation burns more blue than gas which produces more white smoke when burned but is still slightly blue also. Many things can cause a puff at start-up including oil getting into the exhaust or intake system.

 

Mine has done that since i bought it with 17k miles! It now has 67k. It us fuel, and unburned fuel will be blue also.

 

This is true for vehicles under 8500# GVWR... the Excursion however is above 8500# GWVR, there is no O2 sensor downstream of the CAT. You can straight pipe a Super Duty right off the manifolds/headers and it won't cause any problems, it will only make it run better and sound more awesome.