Just use ordinary engine oil, not worth getting a specific oil, its
only a couple of spoonfuls. You wont find straight engine oil other
than at specialist supplying the classic car market, most ordiunary
oils these days are around 15W40.
In case you weren't aware, don't use synthetic oil in your V8, they
prefer a nice thick oil like Difflocks Silvex classic
1984 110 2.5D
Medway Military Vehicle Group