Jin wrote:Do Halfords even still sell oil?
Yes, not only do they sell oil, but as Geoff has spotted they sell a 20w50 Classic Oil at a better price than many of the other brands that offer similar products (Millers, Castrol, Penrite. et al). As Halfords themselves don't manufacture anything, the oil itself is probably blended by Millers, or one of the other specialist oil companies.
I think the usual price is £19.99, but I picked some up at £12.99 when it was on offer.
This information is of no help to you Justin as your K-series wants expensive synthetic oil to keep it running smoothly. However, the A-series engines in the Mk1s, 2s and 3s need the old fashioned 20w50 oil to keep the gearbox in the sump happy.
For those with engines that have been rebuilt and run-in properly there are some good 20w50 oils with zddp (zinc dialkyldithiophosphate) from the likes of Valvoline and Mobil, but they are in the £30-40 price bracket. For engines that may be burning some oil, or rust proofing the front subframe (i.e. leaking oil) then it is best to stick with a good value 20w50 like the Halfords oil.
I have also heard that Wilko do a 20w50 for less than £5 and I'm sure that would make a good running in oil.