Spingears,
Yes, this is a common practice bordering on scamming. The ‘quickie oil change places’ and the ‘push-em-thru tire places’ bring customers in by offering low prices on the advertised items, but count on talking you into other services which are far from discount. It’s these add-ons which generate the most revenue for them since the advertised items have such a low mark-up in order to draw you in. Hence the hard sell to try to convince you to buy other stuff.
(Also, some of the people that work in these places tend to be sexist and ageist; meaning that they will take advantage of women, teens, and seniors, because these groups are perceived as not knowing what’s needed and what’s not.)
This is not to say you never need the items they recommend. So it isn’t always a scam. They just hope to talk you into it getting it long before you really need it. Here is where a little high-school shop class would come in handy for your grandson. (For you too, for that matter.) It’s important to know how often you should change your engine oil, transmission oil, radiator fluid, etc., so that you don’t have to trust strangers who are pushing products and services.
You mentioned that your grandson’s car was fairly new, so I question the need for a radiator flush already; but maybe it’s older than I’m inferring or maybe it hadn’t been well cared for. As for the oil pan gasket, that is something you don’t change until it’s leaking, or until you get the transmission fluid changed (when that’s done the gasket will be changed automatically). So in my opinion, that is unnecessary (based on the limited info you’ve given).
You may use the following as general guidelines, although there are sure to be other people with differing opinions. (These are what those places typically try to push.)
Engine oil change : 3,000 to 5,000 miles. ($20) (Oil places say sooner, auto mfgrs say later.)
Air Filter : Every 5-6 oil changes, or when dirty. (Can be done yourself - easily. $5-$15.)
Engine Belt : Every 2 years. ($20-$50.)(This does wear out, and is a problem if it breaks on the highway.)
Transmission fluid change : Every 2 years. (Watch newspapers for coupons and you may find a $20 special instead of the usual $60; but they will push services you may not need, and will have horror stories to help you decide. Sound familiar?)
Fuel Filter : Only every 3-5 years.
Radiator Flush : Only every 5 years.
Brake Fluid Flush : Only if there’s contamination (rare); after 8-10 years. (They will often put their finger in the brake fluid reservoir, wipe some sludge off the bottom, then give you a horror story; don’t believe it. If you’re really concerned, take the car to a mechanic you trust and get his opinion.)
Disclaimer: I’m not a professional mechanic. I’m the shade-tree variety. But the figures I gave come from an auto manufacturer’s maintenance handbook. Take it or leave it.