Unless it is blatantly driver error, (chucked down a ditch, run out of oil after suitable mileage, etc), then at 3 months / 3000 miles I will repair anything on an RTB Basis, (stated on my invoice), and up to 6 months / 6000 miles I will repair non "Service Items / Wear and Tear Items.
I PDI them thoroughly, if I don't think Brakes, Tyres, etc have 3000 miles in 'em, they get changed !!
I would put a bulb in a car FOC up to 6 months.
It's just good Customer Relations.
99 % of my Customers are repeat business, and out of around 65 sold this year I've only had one back, 2008 Focus 1.8, billy done 2000 miles and just over 3 months in, it lost all compression on No2 cyl, no sign of being cooked or owt !!
As soon as he rang me my reply was "No problem sir, bring it straight back I will look at it for you.
Inside a week he had it back......................
Guaranteed Used Engine sent to me on a pallet £350 plus an easy days work, Oil / Filter / A/Freeze was all it cost me, guy was over the moon, recommended me to a fella who just bought a 2011 C Class Wagon off me recently !!
I'll tell any of you "What goes around comes around"
The other thing is, if you are one of the Dealers who think you can sell Cars for smaller profits than the well established traders, think again !!
This is why we get moaning and groaning, you need a good profit to make sure you don't lose money on any come backer quackers
Also, selling old shitters with more than 75k Retail is just asking for grief, especially smaller engined stuff.
Much prefer a slightly more leggy luxo that a 1.0 small car
*75k miles