Had a used oil analysis done on my last oci, 02' F150, 5.4L, came back as 12% fuel dilution. Was advised to change pcv(1st time) and air filter(13K), which I did and also the fuel filter(2nd time). I was running Amsoil S2K 5W-30 for the summer, oil was in for 5 months with an MC filter(802s) which started to get noisy so I thought the ADBV was getting weak so I did the oil change. I know 5 months and 3600 miles is short with Amsoil but the 5 months was bothering me. Truck has 46K on it and I have the extended warranty. Am running Amsoil 5W-20 for the colder weather now.
Any thoughts/ideas?, thanks

 

The general maintenance items that you have replaced are going to help but 12% is a bunch. There are several ways this can happen and until you get it figured out I would suggest changing oil every 90 days max. You can have injectors that are bleeding down allowing gas to enter the engine when it is turned off. You can have a malfuncting fuel pump that is over pressurizing the system. My best guess though is that you are making very short trips and the engine hardly ever reaches full temp for much time if at all. If this is the condition that you are using the truck, you might want to consider using the cheapest, Ford speced 930 oil and change oil/filter every 3 months. Or change driving habits to longer drives to get the fuel out of the system and get rid of the sludge that is bound to build up with short trip driving. I wouldn't suggest wasting the money on Amsoil until you get it figured out. You might also want to run a large bottle of Ford approved Techron thru the bottom half of a tank of gas. This may help clean any injectors that are slightly fouled and maybe causing a leak down condition. Usually though, the cleaners are a temporary fix and replacement required or sonic cleaning can also be helpful.
One other area that may be suspect, the report may not be accurate. It happens even to the best of them. If you take the dipstick out and give it a once over with the nose, the gas should be very noticable at 12%. If you smell gas on the dipstick- its time to change oil and know that the problem still exists.

 

You're right, all I do really is city driving. Work is 7 miles each way. I kept a sample of that oci just in case the one I mailed had gotten lost. I did check that yesterday and NO noticable fuel smell at all. I may try the Techron.....thanks for the opinion.

 

Labnerd, after re-reading my uoa, carefully this time, it actually says 1.2% not 12. I had to increase the print size of my Adobe readout to see my mistake/decimal point. Just apologized to the nice guys at Bob is the Oil Guy.com. After you suggested the gas smell, which I don't have, I knew I had to have missed something on the report, Again, apologies and thank you for the help.