When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
So a guy was changing the oil in his 7.3 gas and realized he had put 5w20 instead of 5w30 in the engine at the last oil change 3,000 miles ago. I wouldn’t think this to be too big a deal especially during the winter in northern Minnesota. However, I’ve heard that this engine utilizes a variable pressure oil pump. Hope it wasn’t too bad for the engine. What do guys think? Asking for a friend.
Last edited by Slowthump; Mar 4, 2023 at 03:58 PM.
Reason: wrong oil weights
I was under the impression folks were doing that to get a bump in fuel mileage. My 5.4 Triton called for 5w20 so it can't be all that bad, can it?
Manufacturers are under extreme pressure to meet CAFE fleet standards, which continue to get tougher. While I think our Super Dutys are exempt, there has been a push to use these thinner oils as part of numerous small steps to squeeze 1mpg extra.
I’m not a fan of those oils except under extreme cold, low load conditions. Many manufacturers who used to say 5w20 have switched back to 5w30.
I think the gentleman who is the topic of this post is fine, however.
I think it's fine and wouldn't worry at all, but I wouldn't tell the dealer if you go in for engine warranty work, those clowns might deny a claim like roller delamination.
Ford had publications out when they first switched the Modular OHC engines from 5w-30 to 5w-20 for the North American (U.S. and Canada) market. They explained why they made the change (CAFE) and that the 5w-20 still met their standards for use in the Modular OHC engines. The rest of the markets the Modular engines were sold in still specified 5w-30 oil. Ford even changed the engines back to 5w-30 (6.8L, 6.2L, 5.4L, and 4.6L) once they were only fitted in vehicles that didn't need to meet CAFE standards anymore.
The 7.3L though is not a Modular engine and there is no testing at least made public that verifies 5w-20 meets the 7.3L standard. What it is doing or not doing in the 7.3L engine is a wild guess at this point.
Ford had publications out when they first switched the Modular OHC engines from 5w-30 to 5w-20 for the North American (U.S. and Canada) market. They explained why they made the change (CAFE) and that the 5w-20 still met their standards for use in the Modular OHC engines. The rest of the markets the Modular engines were sold in still specified 5w-30 oil. Ford even changed the engines back to 5w-30 (6.8L, 6.2L, 5.4L, and 4.6L) once they were only fitted in vehicles that didn't need to meet CAFE standards anymore.
The 7.3L though is not a Modular engine and there is no testing at least made public that verifies 5w-20 meets the 7.3L standard. What it is doing or not doing in the 7.3L engine is a wild guess at this point.
I vaguely remember thread/ posts from the past of guys using 5w30 even though 5w20 was being speced, 5w20 was too thin for their liking and the engine wouldn't live a full life and have early catastrophic failures. Which wasn't the case.
Let’s look at 5W-20 vs 5W-30 again. The 5W-20 will remain a little thinner at operating temperature, as indicated by its lower “20” number, while 5W-30 will provide a slightly thicker lubricating film.
Oil isn't that expensive. I'd just change it for peace of mind and be done with it.
Modern synthetics and blends are are so thin to begin with, the difference between a 5-20 and 5-30 is almost impossible to tell. And with the highly advanced additives packages they perform almost identically, except at the higher temp extremes. Not like old conventional oil when you could see the difference in flow between the 2 and feel a difference in the way an engine ran. If it's that much of concern to you a dump and refill isn't really a huge cost.