oil burning and pinging thoughts

[Digital2k2]

I've been wondering if synthetic would make any difference in an oil burner as far as pinging and the need for higher octane fuel..

I imagine most of the pinging would be due to the oil constantly being burnt and lowering the octane of the fuel, but would some of the oil leave deposits behind that could heat up and cause detonation? If so, would synthetic be less likely to leave deposits due to it being more stable at extreme temperatures?

The vehicle I'm thinking about switching to dino is burning around a quart in 3k miles through the valve stem seals.

It'd be interesting to have a pole to see who's burning the most oil while still running synthetic.

 

[ARCOgraphite]

Even minor deposits on the pistons and CC will cause pinging or even knock. I would work on that. Maybe a carefully performed peroxide and alcohol ingestion after an Italian Tuneup. Also try a HM oil Like the New pennzoil HM 5w-30 bronze jug, It stopped a cup-a-week habit that our 09 forester had. Consumption went UP for 2 weeks then dissapeared. Hyper Cleansing?

 

[mechtech2]

Both burned oil and liquid oil raise the compression ratio.
They take up volume either way. Knocking can occur .
The oldest trick in the book is using a thicker oil to stop burning or leaks.
HM oils are a bit thicker in their range, with some other benefits.
You could go either way with a full synthetic. It may use more or less, and knock more or less. This is a highly individual case thing.

 

[Digital2k2]

You know I hadn't even thought about trying HM oil.

There's a TSB out on this engine about the valve stem seals, but of course it's just now starting to burn enough now that it's out of warranty.

Only 48k miles and been running synthetic since 2nd oil change.

 

[CBR.worm]

1 qt in 3k miles doesn't sound that bad. Does it smoke? Did the pinging and oil consumption start together?

 

[firefighter]

Just curious, what vehicle is this?????

 

[Digital2k2]

It does smoke. Seems as the oil burning gets worse so does the pinging (normally use top tier gas and a fuel system cleaner with pea every now and then).

It's an 06 lacrosse cxs with the 3.6 liter.

I'm looking forward to trying the HM oil. It's only a few thousand miles on PP 5w30 and a P1 though, so it'll probably be next year till it's ready for a change.
Would like to run 10w30, but I'm hesitant due to the short trips it sees quite a few times a week combined with the cold weather.

 

[meep]

this is not an octane issue. you have carbon buildup, raising compression. this is a case where "bottle fixes" can work.

1. most effective would be a full seafoam treatment where it sits for a while after ingesting the stuff.
2. techron/whatever in the tank a few times will help.
3. or, higher octane gas will mask the problem, and you might pick up a few hp.
4. 10-30 oil, or other thicker oil, a no brainer. syn/no syn, no difference here. A 10/30 HM oil would be fine, especially if it helps the valve seals. (i don't think you'll find a 5/30 hm oil??) but if it's that bad-- ditch 5/30 for good anyway.

 

[SteveSRT8]

despite what was said here even a small amount of oil significantly LOWERS octane rating.

A slightly heavier oil sometimes helps, but it can take some experimentation to find the right one.

 

[crw]

I would start with a very careful look at the PCV system. I have a Mazda which, I thought that the PCV was clean because I purchased and installed a new PCV valve. But the problem continued...

It turns out that the PCV rubber hoses were completely blocked (from a previous owner) and even the ports on the valve cover were all gunked up. I needed to use a drill bit, and by hand chase out the ports where the PCV system was plugged. Finally, after that the car ran well.

Perhaps it's not the PCV, but the symptoms are the same and it's an easy (perhaps free) thing to fix.

 

[IndyIan]

I assume you do run 91 or 93 octane? Does it still ping with premium fuel?
Also I guess you could buy a digital service manual off of Ebay and see if you can manually adjust the base timing so it doesn't ping as much.
I don't ever hear of the old Honda's pinging due to all the oil they burn but I've never asked any of the guys in my motorsports clubs if that happens.
I guess they regularly beat the "tar" (maybe literally!) out of their engines so carbon build up isn't an issue.

 

[crw]

The more I think about this... changing your oil is not going to help. Something is broken or gummed up. Fix that, and then perhaps change your oil and fuel to prevent it from happening again.

Oil burn and pinging are exactly what I saw with a clogged PCV system.

 

[meep]

^^^ very interesting. never seen this... but i could see it making sense.

 

[Digital2k2]

This car has never had anything more than 87 octane. It usually only pings under light acceleration and oddly between shifts, but not consistently.

Since it just had a treatment of techron and the pinging has been getting worse as the oil consumption increases,I'm hoping a slightly thicker oil will take care of most of the problem.

I actually didn't mean for this thread to get vehicle specific. Still when I think about it, it seems like a synthetic coming past the rings or valve stems would be less likely to leave deposits behind as it makes its way to smoke out the tailpipe haha.

 

[BearZDefect]

Originally Posted By: Digital2k2
Still when I think about it, it seems like a synthetic coming past the rings or valve stems would be less likely to leave deposits behind as it makes its way to smoke out the tailpipe haha.

Why would it leave less deposits than a conventional oil?