mechanic told me to use 20w50 engine oil in my 1994 Lincoln town car 4.6L v8?

[I Ate Your Keno Ticket]

it uses a quart of oil every 8 to 10 days plus blue smoke comes from the exhaust when i take off from a stop he said these engines are notorious for worn valve stem seals should i use 20w50 right now i use 10w40 and please don't tell me to use 5w20 or 5w30 that stuff is like water then i'll probably burn up a quart every 2 days if i use that stuff "lol" recommendations expire after a few 200,000 miles or so