... I'll tell you what National tyres would have done if for and you woudn't need to get your hands dirty.
Ah National Tyres oil change offer...Winchester branch.
I phone to ask them to book it in
"What car?", they said.
"Kit car with Lancia Beta engine"
"Have to look that one up... we haven't got the oil filter - have it on Wednesday".
I drive the five miles to National tyre the same day to check.
"Happy to work on this car?", I ask
"I want the fully synthetic oil of a viscosity range of my choosing" (explained engine in back of car, higher running temp than might normally be)
"Ah, we're changing our oil suppliers - haven't got stocks of everything"
then some more stuff about QXR 10W/40 oil, semi synthetic not fully synthetic. Decide to go risk it and chuck it out at 3000 miles like mineral oil, or earlier if I don't like it - it's still a cheap oil change.
I roll up at the appointed time (about 4pm).
"Here for an oil change"
"Sorry, filter hasn't come - be here tomorrow"
"OK, cancel the filter please. I'll do it myself".
Check they have the filter and can get it. Make sure they can get the oil you want and your car needs. Use the web site to check but be aware that the oil recommendations are based on just three oils mineral Hypergrade 15W/40, semi-synthetic QXR 10W/40 and synthetic Visco 7000 0W/40. The web site did not recommend the correct oil for my old Ford Mondeo (in fact very wrong) so watch out here.
Of course this might all be my fault for knowing what I want, but if I'd had an old Mondeo, I could have been heading for trouble with 15W/40.
do it yourself.