Post by
D1dad »
https://forums.nicoclub.com/d1dad-u301036.html
Sun Mar 03, 2024 5:40 pm
My 09 Altima did the same and I bought it new with 3-4K oil changes. I swapped out the engine for a low mileage shortly after Nissan replaced the cvt under warranty. I figured the rings probably never seated. The pre cat wasn fully in tact so it wasn’t that. More than likely, someone neglected it and it’s sludge like vstar said. I’d try the new valvoline clean and protect oil which is supposed to clean the engine back to like new, or if you wanna spend some money try hpl lubricants 0w20 which is liquid gold. I dealt with it for close to 100k with next to no issues or improvement and Nissan kept telling me it was acceptable.