Hi, thanks for having me on the forum. This has always been my go-to place for oil related inquiries so I hope to get some advice tonight. It's sort of an odd situation but I'll try not to run long.
Basically, I purchased a 1995 Chevy 350 from a pick up and have adapted it for marine use to replace a 305 that overheated.. As I was tearing the new 350 down to marine-ize it, I found some sludge in the valvetrain and in the lifter valley. I scraped, vacuumed, wiped and then washed it all down with a few gallons of diesel, making sure all oil ports were clear. I elected not to pull the pan and open up a bigger can of worms, because from what I hear in most cases it's best to not disturb the sludge. I plan to just clean it out slowly with high detergent oils. It was not what I would consider extreme, just a thin black coating in most places.
Anyways, I have the engine in the boat and it runs well with no odd noises or issues. BUT it seems to have extremely high oil pressure, confirmed on my mechanical test gauge. Around 45-50 PSI at IDLE, and up to 75 at 2500 RPM under load. I have not let it get any higher than that because I'm sure it would spring a leak. Those figures are at normal operating temperature, which this time of year isn't very high on a boat.
I have 10w30 Farm & Fleet (Citgo) full synthetic in there now, as a clean out/test run oil, and because I had been running this oil in the old motor for many many years. The truck application called for 5w30, and the marine versions of this engine call for SAE30 (later back-rated to use 25w40 syn blend). There are no internal differences between marine and truck 350s of this era, so it's safe to assume I could use either one of those oils, although of course, the marine oil would better protect under constant load and against corrosion.
Either way, I need to do something to lower my oil pressure, and switching to 25w40 wont do it! I am almost certain sludge is causing some restriction in places, so I would like to use a heavy detergent oil and short OCIs to clean this motor out. I am considering dropping down to a Mobil 1 5w20, or at least 5w30, with M1 filter...
I have to take into consideration the type of use it sees...these motors have a 140* thermostat, and I also idle mine a lot for fishing. So not only does my oil not get hot, but I also get some fuel in it from this kind of use. Am I on the right track with my oil selections, or is there a better way? The last thing I want to do is blow it up, or have to pull it apart for repairs again.
Thanks for any and all inputs!
Basically, I purchased a 1995 Chevy 350 from a pick up and have adapted it for marine use to replace a 305 that overheated.. As I was tearing the new 350 down to marine-ize it, I found some sludge in the valvetrain and in the lifter valley. I scraped, vacuumed, wiped and then washed it all down with a few gallons of diesel, making sure all oil ports were clear. I elected not to pull the pan and open up a bigger can of worms, because from what I hear in most cases it's best to not disturb the sludge. I plan to just clean it out slowly with high detergent oils. It was not what I would consider extreme, just a thin black coating in most places.
Anyways, I have the engine in the boat and it runs well with no odd noises or issues. BUT it seems to have extremely high oil pressure, confirmed on my mechanical test gauge. Around 45-50 PSI at IDLE, and up to 75 at 2500 RPM under load. I have not let it get any higher than that because I'm sure it would spring a leak. Those figures are at normal operating temperature, which this time of year isn't very high on a boat.
I have 10w30 Farm & Fleet (Citgo) full synthetic in there now, as a clean out/test run oil, and because I had been running this oil in the old motor for many many years. The truck application called for 5w30, and the marine versions of this engine call for SAE30 (later back-rated to use 25w40 syn blend). There are no internal differences between marine and truck 350s of this era, so it's safe to assume I could use either one of those oils, although of course, the marine oil would better protect under constant load and against corrosion.
Either way, I need to do something to lower my oil pressure, and switching to 25w40 wont do it! I am almost certain sludge is causing some restriction in places, so I would like to use a heavy detergent oil and short OCIs to clean this motor out. I am considering dropping down to a Mobil 1 5w20, or at least 5w30, with M1 filter...
I have to take into consideration the type of use it sees...these motors have a 140* thermostat, and I also idle mine a lot for fishing. So not only does my oil not get hot, but I also get some fuel in it from this kind of use. Am I on the right track with my oil selections, or is there a better way? The last thing I want to do is blow it up, or have to pull it apart for repairs again.
Thanks for any and all inputs!
