I've noticed more oil leaks on the garage floor in the last couple years. I'm running mobile 1 full synthetic 5w30. Should I change to something thicker to reduce this or is there a better option? The engine has had nothing more than top end upgrades in its life.

 

thicker wt oil will not solve a oil leak.

with that said engines with high milage can move to a 10-40 wt to help maintain a good oil wedge between bearing surfaces....this however is not a oil leak preventative. Seals and gasket failure cause oil leaks. Any different oil does not rectify that

 

How many miles? What is the oil pressure at idle?

Where is oil leaking from? Did you ever have the leak at the rear/passenger side of the intake manifold? Have you checked the valve cover gaskets? Possibly the various timing cover seals? Possibly a leaking oil pressure sensor? Loose oil filter mount? All of those are repairable.

 

120,000. It's just under 1/4 on the gauge when warm and idling. I think that's around 18 psi. I never had the manifold leak but the valve covers appear to leak. I put new gaskets on years ago but it didn't help. On another vehicle I put fresh cardboard under the vehicle and traced it up to the area it's leaking from. That should help locate the area so I can see if your suggestions are the cause. I've been driving Chevy's my whole life and they all leak oil. Everyone says it's a Chevy things.

 

I am of the belief that the original manufacturers oil recommendation is based on a new, stock engine, with stock bearing clearances, used under normal conditions, and may need to be reevaluated as an engine ages.

That being said, there are a number of things to consider. First, too much oil pump drag (too thick of a motor oil, BBC pump, etc) on an aging OEM plastic oil pump driveshaft adapter is a potential disaster. Second, thicker oil is not a bandaid for a worn out engine. If an engine is worn, it’s worn. Third, many of these engines have oil coolers and all have bypass valves, both of which can contribute to a loss of pressure. Probably a couple other things as well I’m not thinking about at this moment.

Generally, if someone has decent oil pressure when driving but it’s down on pressure at a hot idle, and the oil isn’t significantly aged or the change in pressure isn’t sudden, changing from 10w30 to 10w40 and monitoring the change might be a good thing. If this fails to help significantly, replacing the filter bypass or checking the cooler for flow (they are known for plugging up) might be something to consider.

If for any reason you need to pull the intake, replace the oil pump drive adapter with a billet one with a new melonized gear. Tick sells them both. ALL LT1’s are at the age where the OEM pieces should be lifecycled out of service, IMO.

If you are around 18 at idle that should be fine. You can try to go with a slightly higher viscosity oil and see how that helps. I prefer to see more at idle, however I believe the minimum spec is 6-7 at idle (don’t quote me on that).

As far as you oil leaks go, are you sure you aren’t having an issue with crankcase ventilation, or blow by pressurizing the crankcase and forcing oil to leak? How do you drive it? Does it smoke at all?

 

Excellent response! The by pass valve and cooler problems, plastic drives..