Lehtos latest video discusses an issue I’ve worried about for a long time. How does one document maintenance so they can be assured of not getting screwed if they try to make a warranty claim?

I really depends on the claim and more importantly the manufacturer. I'm a tech at a Toyota dealer and do warranty repairs all the time without any maintenance records at all but Toyota is pretty good about "just repair the car and make the customer happy" The only time they want some type of records is when the customer wants a repair after the warranty is expired.

Gus

We have all our maintenance done at the dealer, we're even buying tires from them, they're having a buy 3 get 4 deal now that beats Discount Tire. I usually get an alignment and four tires for what Discount gets for 4 tires. We can't afford their batteries ($500+, gulp) at the dealer, but everything else they're doing. All my receipts are in file folders in the cabinet "in case something gets lost" (yes, that happened at a mechanic shop I worked at in the '70's, it was a vindictive thing, lesson learned from others misfortune). The dealer currently has my 300 in for oil change, inspection, coolant and brake fluid flush, should get it back tomorrow.

The dealer also gave us a carfax account, all the maintenance is logged there as well. Interestingly, you can also log any maintenance you have done that doesn't otherwise show up on carfax on carfax.

Dad used to buy oil by the case, keep the oil and filter receipts, perform and log the service in his book, I doubt that would fly these days. I seem to recall a story here about Hyundai denying a warranty claim on a dealer serviced car because they didn't log the VIN?

that is really a bad case to site for needing to keep all your receipts and such.
It is a used car someone bought trusting the person they bought it from to have done all the maintenance.

I know I wouldn't take someone's word for it. I would verify or change parts right after I bought it if it was on the boarder for having it done.

as for needing receipts, the only example he gave that might make me pause was if the car had a known sludging problem, and I needed to prove it. But even then, I think that is a bit rare for someone that actually maintains their car and checks the oil etc...

I’ve done almost all my own oil changes for 40+ years with few exceptions. The exceptions being “free” oil changes I’ve been given with new car purchases.
I change my oil regularly using top brands and Wix/Napa filters. Never had an engine problem. (Knock wood).
Never kept much in the way of records of them though either.
I bought my 6.4 Ram last April and at under 4000 miles I haven’t had an oil change yet. I didn’t get a free oil change offer with this purchase. I’ve been planning to get the oil changed at a dealer very soon, if nothing else to let them remove the oil filter on the chance they still have “Mongo” installing the filters torqued to 200 ft-lb at the hemi engine assembly plant as has been the case previously.
6.4s sometimes have lifter/cam issues and I want to be covered if that happens with mine. I’m concerned if I do my own oil changes how to document that adequately so the dealer couldn’t deny? Reciept doesn’t prove anything except you bought oil. And receipts these days are printed with ink that often vanishes after a year.
So what to do, make videos of oil changes holding up the days newspaper to prove done?

I've always kept the receipt for the oil and filter. I also keep the filter box top writing the mileage and date on it. i staple the two together and put them with the owners manual

I've bought a few vehicles new and rarely kept oil change receipts as most were done by me. Have yet to have engine/trans issues. I have had multiple issues with other components that were taken care of under warranty on a Ram I owned. Ball joints, radiator, rack and pinion, ring and pinion(frt and rear)...the list goes on. None of those repairs required proof of maintenance.....they did, however, force me to buy a different brand truck that has been much less "needy" on the repair front.

When I change the oil in my home garage, I snap a picture of the filter, oil, receipt, mileage of my car and even my car on the ramps. Usually I try to take the picture of the receipt with the odometer. This way I have all the info I need in my phone and can easily share pictures if needed or go back to double check when I last changed oil.

One bad thing about Hellcats and Scatpacks… warranty demands are 6000 miles, or SIX MONTHS.

My 2020 Scat is a garage queen. 1700 current miles (400 of those was driving to have Ravelco installed.

Because of the six month demand, I’ve already had the oil changed three times at the dealer at over $150 a change.

First time (800 miles) the service manager thought I was nuts.

When he said Dodge wouldn’t decline a warranty issue over the six month clause, I wasn’t chancing it.