1985 300TDT - Took vac reading from one of the connections off vac hose (from vac pump to brake booster) at idle - reading was 20 in. From what Ive read - is this normal? Car has about 125K miles. I've read about (in this forum) oil in the air cleaner getting in there by way of a "tear" in the vac pump diaphragm. If a tear happens - there should be A LOT of oil in the air filter, and vacuum reading would be lower than 20 in?? Thanks.