Comments on My Theory

Joined
Dec 28, 2011
Messages
3,347
Talking about 2006 Nissan Sentra 1.8

Bought it with 159k for $500 and needing some basic love. Front and rear struts, plugs, drain/fill coolant, drain/fill manual trans, PCV, clutch fluid, and check engine light was on. Gas mileage was about 18 MPG IIRC. Had a code for bank 1 upstream O2. Replaced the O2 and mileage went up to 31/35 where it should be. I have about 6k miles on this and reported some oil burning. Previous owner is a good friend and he had done dino 10-30 at 3-5k OCI. He stated no oil burning issues. We are pretty close and he isn't one to lie or BS. I found it odd. After replacing the O2 and resetitng the check engine light returned with the same bank 1 fault.

I could hear an exhaust leak but figured I'd get to that eventually. Fast forward....I brought it to a friends shop and he found a rusted out bracket that caused a hole in the exhaust just before the downstream O2 sensor. He sleeved the hole and seems to be all good. We pulled the bank 1 O2 and it was heavily sooted. The oil was very dark for a well kept engine and smelled like gas.

Am I likely correct to believe that the hole in the exhaust just before the downstream O2 caused the engine to run rich and fuel dilution of the oil? The check engine light has remained off since sleeving the exhaust. The sump on the 1.8 is so minimal so I figured it a good idea to dump the 5-30 ST and put fresh oil in. Time will tell if it ends the burning.

Before the exhaust sleeve, I added 1 quart over 1700 miles.

I figure I'll run this OCI a little over 3k and send a sample to one of the lower cost UOA labs just to see what comes back.
 
Joined
Jan 4, 2016
Messages
1,524
Location
NC
I think you're spot on with that theory. With a small sump like that I'd run nothing, but synthetic. Supertech synthetic is plenty. And I'd stay with 10w30, as it will have less viscosity modifiers than 5w30, which usually means less varnish and oil deposits inside the engine. Depending on your location and climate, 10w30 could be used year-round, especially a full synthetic.
 
Joined
Jan 4, 2016
Messages
1,524
Location
NC
Some good numbers for a budget synthetic 10w30 here.
 

Attachments

  • ST 10w-30 SYN.pdf
    53.4 KB · Views: 11
Joined
Aug 22, 2009
Messages
5,260
Location
Pittsburgh,PA U.S.A.
While it is more likely that it will burn oil regardless of the brand of oil, there have been post here on BITOG when someone found that there engine burned oil with one brand, and not with a different brand.

And it may be that it was burning oil with the previous owner, but did not get low enough to trip the low oil pressure light during one oil change without adding oil, and the previous owner never checked the level.

It might be a good idea to start by asking the previous owner what brand and viscosity of oil they used in it in the past, and try that oil to see if the consumption becomes negligible while that oil is used.
 

BISCUT

Thread starter
Joined
Dec 28, 2011
Messages
3,347
Previous owner used 10-30 dino at a 3-5k OCI. I should have 1500 miles in a month so I'll know what's going on by then. The sleeve appears to be working. No codes after 200 miles. In the past a reset caused the code to clear but returned within 25 miles. Safe to believe no more running rich.
 
Top