As a cerrified Tribologist I can tell you a few things you might consider about your OCI. The Walmart synthetic oil is made by 3 vendors, either Warren, Saftey Kleen, or Mobil/Exxon. If you look on te bottom of the bottle and see a WP it's Warren, or it says Safety it's SK, or if it says M/E it's Mobil. The specs are not very great really. Any great oil has a good base oil and an equally good additive package. Walmarts synthetic is a Gp III base oil and if it's SK, it's recycled oil that gone thru an ISO/SYN process. The additive package is ho-hum at best. That's not said to beat the oil you've been using down, it's that you can do better for less money. Motorcraft oils have been subsidized by Ford for years and is the absolute best on Walmarts shelf, including the synthetics. The MC formulation includes borons for increased lubricity as well as moly for when things get hot. It's about a 50% synthetic base which is an acid washed white base which means it's incredibly pure. It's designed to go the distance in that Triton of yours. Next oil down the list would be the Pennzoil Yellow bottle which out performs their own synthetics. I'm assuming you are using the required 5w-20 oil. If not, you need to consider it. The thinner oils are for real and provide more thermal protection than a heavier oil. As you probably learned in high school science class, a thin fluid will absorb heat faster and release it faster. Works the same with motor oils and a modern engine toiday depends on the oil for about 20% of the cooling capacity. You didn't state the year model but if it's a 3V engine, you have the cam phasers and VTC that requires the 5w-20 to work correctly. Otherwise pressures build too quick and the system runs in advanced mode which can lead to a jammed phaser-a 1500 dollar fix per side. You'll find the blends turn in the lowest wear metals in analysis and you get the best of all the base oils using it. No base oil provides more lubricity except the esters and there is only one ester based oil on the market and that's G Oil. The extra lubricity it brings is so little you or your engine will ever know it. It's only available as a 5w-30 and has a so-so additive package- not really worth the premium. No base oil will make your engine last one mile farther so if you think the synthetics provide for longer engine life- you'd be wrong. The guy with the million mile Ford van with the 5.4 just had his engine die at 1,300,000 miles and used the cheapest crap he could buy. If you just like using the Walmart synthetic, keep at it and keep changing it at 3000 miles. It doesn't hold up that well in any form of extended OCI. Otherwise I would suggest using Motorcraft 5w-20 blend and changing every 6000 miles. I change my Triton at 7500 miles and it goes thru the lab everytime with TBN above 2.0 and single digit wear metals. It's now at 111,000 miles on the meter and I expect it will last longer than I'll have it.
FWIW, for you Mobil One users, the regular Mobil One in 5w-30 only has been failing IVA testing which is a cam wear test. It's failing at the rate of 3 times the allowables. Mobil has been silent in regards to questions asked about it. If you have a flat tappet engine, use their Extended EP version. If you have a roller cam engine, it's not an issue.
