Driving your vanagons up to 85MPH will actually present a risk to valve
tips. I once drove my 84 vanagon to Las Vegas and I drove it up to 85+
MPH for an hour or so. That was when the vanagon was at about 50+k miles.
It is now at 119K miles and I have found that it has 2 or more valves that
have excessive wear on the valve tip. The engines now has developed into an 
air cooled bug engine sound, which is much like the familar normal valve
tapet noise on bug engines. But vanagon engines use hydraulic valve lifters
and are not supposed to have tapet noise at all. I think this was caused by
my careless high speed run on my way to Las Vegas, which is proven to be
a unnecessary gamble I did on my vanagon. Now I keep at below 70MPH when I
drive my westy.

David Kao
83 westy, 84 vanagon