PROS: It may just prolong the life of your faulty engine ...
past 10 years / 150,000 miles, GM no longer cares - even though it ought to last 25 years / 250,000 miles.
If your L87 does not make it to at least 200,000 miles, GM wins, you lose.
CONS: GM doesn't recommend 0W40 for engines that are 'within spec'; more expensive, slightly worse MpG,
maybe GM determines you haven't been using the recommended oil and gives you a hard time [over future engine repairs/replacement] ...
Note that GM failed to suggest / recommend 5W30, as prescribed for the 6.6L L8T.
A set of facts being ignored are as follows:
1. Physical spec design & manufacture similarities between the LT1 (0W40) & L87 (0W20)
vastly outnumber any differences that would be affected in any way by 0W40 vs 0W20
2. Biggest reason for GM to spec 0W20 vs 0W40 is CAFE MpG test scores
Nelly, and anyone else wondering:
if you want to try to keep your L87, 0W30 / 5W30 / 0W40 / 5W40.
Used motor oil analyses will better inform you than reading emotional conjectures that resemble Soroborou, the snake that shoves its head up its own arse.
if you want to try to have GM replace your L87 before the warranty expires, 0W20.
Unfortunately I've not been able to think of anything else that can be done to make the L87 fail prematurely. (Maybe drive it with more gusto?)
Wonder why no one else has either.
