Originally Posted By: Drew99GT
Originally Posted By: ThirdeYe
Originally Posted By: Drew99GT
I'd be more worried about the cooling system than the oil; Upper manifold EGR stovepipe leak, lower intake manifold gaskets, and heater hose elbows. Oh, and the oil pressure senders and oil filter adapter gaskets like to leak. Get all that stuff squared away and keep running whatever oil you like and it will probably get way over 200,000 miles. I've used nothing but Conventional in my Dad's 99 Olds 88 and it's nearing 230,000 miles and doesn't consume a drop of oil now that the pressure sender and filter mount gaskets have been replaced. I run 5w-30 whatever's on sale conventional in winter, 10w-30 in summer. Bright clean shiny metal under the valve covers.
Do you see any reason to change the oil filter and pressure sender if they aren't leaking? I believe the leak in my Firebird is coming from the rear of the engine (rear main or oil pan, probably). I do notice that the oil pressure gauge seems pretty inaccurate, so I'm not sure if that's a symptom of that or not. Mine is always between 60-70psi... which seems odd to me. Shouldn't it go down once it's warmed up? At hot idle, it's just a hair over 60psi. Cold idle is closer to 70. When driving around, it's at 70psi whether it's hot or cold.
That oil pressure behavior does seem wrong. The gauges in the older GMs are in fact real and not "dummy" gauges; ie, they will show the actual oil pressure. They usually start out in the 60s cold and go to around 20 at hot idle, and up into the 40s with increased rpms.
Do you find any oil leaking around the oil filter area? The pressure sender is right above the oil filter. When they start to go, it will leak oil out past the electrical connectors and start dribbling down around the filter area. If you remove the passenger tire, you can get a visual of that area to determine if it's leaking; if you pull the connector on the sender and any oil is present, it's bad.
If it's right above the oil filter, I probably won't have to take off the right tire. The oil filter is located right at the front of the engine and I could probably see that area just looking under the hood (it's mounted vertically in this engine bay). I'll take a look when I get a chance. Thanks! I don't remember seeing any leaks around that area when I changed the oil back in May.