This past oil change I switched to synthetic oil for the first time (Royal Purple). Since then I have put on about 3,000 miles, but have had to add 2 quarts of oil. There have been no apparent leaks as I have been paying close attention to see if there have been any after I put the first quart in. So is this due to using synthetic for the first time in my engine that it is burning through it? The only problem is that it doesn't seem to be stopping and there are no apparent leaks. Or else could this be the ever popular plenum gasket problem with 5.9 2nd gen engines? I know that one symptom is excessive oil consumption.

Thanks for any help

 

I've run RP periodically and haven't lost any measurable amount between changes. However, synthetic oil molecules are smaller than those of conventional oil and may expose leaks.

Take you a flashlight and shine it down the throttle body. Any pooling of oil means your plenum has blown...

 

Thanks Hammer, Yeah I had a feeling it might be that. I'll check it out tomorrow after work so well see...


If it is blown how long is it okay to drive with it like that? The reason I ask is I'm doing an internship about 11 hours away from my home, and back home I could use my dad's shop for a space to repair this, but I probably won't be back there until the end of the summer...

 

Its ok to drive as long as you check the oil level regularly. Eventually you are going to have to do something about it.

 

Just checked it out and I didn't see a large amount of oil down there. Maybe a little residue but not a whole lot. Would it be pooling if the gasket was blown? I took some quick pics on my phone but its really hard to tell from them. I'll put them up anyway:

 

The first time I switched from reg to synth I went through 2 qts as well. No leaks, no problems, after that first change it never needed any extra.

 

Yeah i'll probably just keep an eye on the oil level through my next oil change and see how it goes. Also I will probably pull off the throttle body this weekend to get a better look down there and also it could probably use a cleaning too. Do guys normally just use brake cleaner to clean it? And I don't have to worry about disconnecting the battery because mine is not an electronic throttle body right?

 

Seafoam takes the carbon right off. Just a little on a rag or q-tip.

 

Okay so today I took off the throttle body to clean it and it was filthy! The gasket was cracked too so I don't think its ever been cleaned. Anyway I looked down in the intake to get a better look and I did see a little pooling of oil. It was up against the back corner due to the slight angle of the engine. That's why I couldn't see it before. So in the near future I will be doing the plenum fix lol. Probably not til the end of the Summer when I can get back to my dads shop to have more room and tools. I took some picks throughout the cleaning:

Before:






After:








Pooled Oil, a little hard to see it in the pictures: