Don't know anything about Amsoil, but here, again, is a link to a
discussion of Red Line.
http://www.vtr.org/maintain/lubricants-redline.html

Pretty hard to beat starting with synthetic jet turbine oil as your
base.  I never trust anyone who bad mouths his competition.  Amsoil is
sold though a distributor channel, not retail, so they are less than
objective, but it may be a fine product.

And after inspecting the good as new bearings in my MGB tranny after
100,000 miles on Red Line MTL, I wouldn't put anything but Red Line
products in my transmissions (MT-90 is used in the Vanagon).

--
Stuart MacMillan
Seattle

'84 Vanagon Westfalia w/2.1
'65 MGB (Daily driver since 1969)
'74 MGB GT (Restoring sloooowly)

Personal mechanic for:
'70 MGB GT (Daughter's)

Assisting on Restoration (and spending OPM):
'72 MGB GT (Was daughter's, now son's)
'64 MGB (Son's)

Stripped and gone but their parts live on:
'68 MGB, '73 MGB, '67 MGB GT