I'm thinking he forgot to type NOT in that sentence. Usually idling is bad for seating the rings but I would also assume test drives involved some lead feet, like my Wife did. Hah.
New vehicle has 5 engine idle hours
- Thread starter QwikKota
- Start date
Also having worked for a dealer as well as living near a GM plant as well as having my own Z06 built and watching it happen...maybe.
It really really depends. Some of the delivery guys drive it like they stole it to the train lot for shipment, some don't. Some customers flog the hell out of them, some don't. The "worst" was when we got the new mustangs and one of the techs had to beat the hell out of it right off the delivery truck. Wailed on it so hard that you could literally smell everything baking off the car so bad they had to park it way out way out for a few hours. All the preservatives and coatings on a new car gradually bake off. This was not gradual, but all at once, and it was pretty obnoxious. The best was pretty much any new work type or family vehicle, they didn't get ragged on at all really.
I would also mention I worked at a very shady dealership. It was nothing for employees to have a knife fight in the parkinglot, etc.
The manual for my CVPI states every 1hr of idle time = 33hr of driving, for PM purposes.
"Too thin for a V8"....okay, what does that mean? I know what your words mean, but say it with math or science. What is the technical reason that you believe it is too light for a naturally aspirated V8 ?
- Joined
- Jul 10, 2026
- Messages
- 169
Yeah, also almost every break in procedure specifically indicates not allowing constant engine speed, there’s a heavy focus on varying RPM as much as possible during break in.
GM made a junk engine, I dunno what else to tell you. My CVPI runs great on 5-20. Oil analysis confirms. It's got 155K miles on it, now.
The viscosity is too low. I will admit I am not well versed in the GM world but for my Hemi, the manual for the older trucks stated 5W-30 was the proper oil weight. The newer trucks changed to 5W-20 without any re-design of the engine such as reduced bearing clearances. This was purely for CAFE standards to increase fuel economy at the expense of engine longevity. The Hemi is know for lifter issues with excessive idling. Higher viscosity helps mitigate this issue.
My Z06 had a very specific break-in methodology.
No constant speeds
No high load
No high RPM
Speeds under 55 or 60mph (not realistic, but is ideal).
Heat cycle it (don't drive for more than an hour or so at a time).
This is of course all "Ideal".
It is meant for the first 500 mi, and then you will begin building toward redline/full load at around 1K rpm.
I did this as close as reasonable, and my Z06 used about 1qt of oil by 600mi, and then no more. Ran great. NO oil usage later, just purred.
The HEMI lifter issues are kindof complex, but not really related to oil weight. An example is my HEMI. It had 100K miles on it and the lifters were fine. OEM 20 weight spec'ed oil was used.
The problem is the oiling of the needle bearings inside the lifters. That's what takes a dump. It does so due to extended intervals and low quality or dirty oil. The real issue came about when they integrated MDS. These lifters use oil controlled locking pins. They are much more intricate and have tighter clearances, and need a clean oil.
Not a viscosity thing really, but you COULD make the argument that a lighter oil may actually be better here as it pumps up from the pan quicker, splashes a bit better, and will reach those pins better. Any stickiness at all or lack of precise oil pressure results in play in the drivetrain and the "hemi tick".
My crown vic has a 4.6L V8. It came out in the early 90's and was spec'ed for 30 weight oil. With ZERO changes mechanically, Ford them shifted to 20 weight. NO issues arose. I use 5-20 like the oil cap says and my UOA is fine.
- Joined
- Jul 10, 2026
- Messages
- 169
My FB20D in the Subaru Crosstrek had a similar process which I followed as closely as I could - especially because it has a CVT so the RPM range is less fluctuated during operation than with a traditional AT. I apparently did it right, as I have zero fuel dilution and zero oil consumption at 42k miles according to oil analysis and dipstick checks. It always puzzles me why a majority of folks don’t give a hoot about following break in procedure.
So, I work with people a lot. People are extremely biased to their own desires and sources. They will discount what engineers and so forth say, in favor of Uncle Snuff's advice to "Break it in hard!" or whatever. Or maybe they read something on Google that contradicts the actual manual or SME's. In short, people are typically extremely ignorant and dare I say, stupid (as they have no desire to cure their ignorance). We see this time and time again.
BrendanC
$100 site donor 2024
Also, this is the procedure I break in all my ICE cars with. *unless* the manual says otherwise for the car specific. For example, BMW states the rear diff needs the fluid changed at or before 1200mi. My Mazda CX5 stated 28,800mi (yes...), my Z06 did not have an interval initial that I recall.
The crown-vic forum is rife with debate here. I don't think the engine cares nearly as much as the pullies, belt, and all the gaskets and other under-hood items subject to heat. Idle hours matters there, IMO, a lot more than rings and bearings.
- Joined
- Jul 10, 2026
- Messages
- 169
Yeah I kinda go off the res for fluids because I do my oil at 500mi, diffs at 1,500mi, CVT or AT before 10k on any new car. It’s always in rough enough shape to justify the change, so I wish it was common practice for dealerships to do all drivetrain fluids by 5-10k miles, it would likely make a meaningful difference in longevity.
The one place I really went off the rails was on the Mazda CX5. They state Skyactiv transmission fluid is for life. I have to this day not seen a single incidence of failure due to fluid ever posted about. I never changed mine and it was fine in both CX5's. I only took one to 105K miles and one to 80K miles, but it was fine, and I saw plenty of posts from 2-300K mile units that were doing fine too. The UOA's I did see from them showed about 20-30% the wear of conventional slushboxes, so it seems born out.
True it did depend, some of the lot guys were better than others in how they treated the cars. Some customers were pretty brutal with them as well, though mostly with the used cars, not the new ones.
The idle time, wasnt done out of malice, really just oversite. We would go out to either move the cars around, or to melt ice off them in winter, after letting them idle for a few minutes. We were pretty close to the interstate so the lot was already noisy, and new cars can idle pretty quietly and sometimes you just missed a few, until you're out there a few hours later and notice a couple of cars still running. Or worse, out of gas. Now we had to get a few jugs of gas, and hope that the battery(s) survived with the ignition on all day.
This was at a nice dealership in a nice part of town.
I'm aware of the needle bearing issue after looking at failure posts on the Ramforum.com I believe they changed the lifters in 2018 to have larger diameter bearings. Not sure which year you had.
I'm not following how a lighter oil would move faster. Wouldn't a heavier weight oil increase oil pressure faster? Either way, there is not a huge difference between 5W-20 and 5W-30 but my statement was based on the fact that nothing in the engine changed to support this like some of the newer vehicles having problems with bearing clearances and machining debris.