Normally its the number one cam that gets messed up, mine wore a hole through the lifter after about 100,000 miles
The car always had 5w40 505.01 spec oil and was replaced at every 10000 miles (shell helix 50000 miles then Fuchs for the next 50000). After camshaft and lifter replacement I started using 5w30 507.00 castrol edge.
A few people posted that the issue was resolved in later cars, but as mine was one of the last MK1's off the line, that clearly isn't true.