Originally Posted By: chad8
I own a 2011 sonata. First generation DI. First owner went 3000+ miles between changes.
I go 7000 with Quaker state 5w20 conventional, which is OEM oil. 7500 is recommended interval.
Car has 58000 on it. Burns maybe 1/3 quart between changes. Hard on oil? Yes, but not any worse than other engines.
Main weak point is carbon in intake and injectors. I clean the throttle body and use good injector cleaner regularly . Also use top tier Costco fuel.
With a 120000 mile , 10 year engine warranty, I'll take my chances on longer oil changes.
I won't own it past 100000 anyway. I'm buying another . At almost 40 mpg on the highway, I wouldn't own any other kind of engine until battery or fuel cell technology gets better.
DI is the present and future. Get used to it.
Well like you said, you're not going to own the car past 100,000 miles anyway. And I agree, direct injection is here to stay (and that's a good thing).
What I keep hearing is that it's tough on oil, I'm not sure if that's true - I suspect it is. But like you said, it's here, it's going to stay, it has its advantages.
I think these systems are improving daily. They will get quieter, they will stop the carbon buildup problem. Not that you care - because you're getting rid of the car anyway - but using good fuel and throttle body cleaner isn't going to stop/clean the carbon buildup problem these engines create. The carbon buildup exists on the back of the intake valves mostly. The only way to remove that is to clean the back of the valve manually - because without an actual injector there, cleaners, solvents, fuel additives, won't actually get to that spot. It's like buying a colon cleanse, opening it, but instead of ingesting it...you pour it on your leg. It's not going to work.
As for the direct injectors themselves, yeah a good fuel is always nice, but any fuel flows out of those injectors at very very high pressures...at these pressures almost anything should keep those spray nozzles clean, I guess. But the problem is the valves are never getting touched...add that to leaky PCV valve systems dumping oil into the intake...nothing is cleaning those valves. Like someone else said - some cars are now using two fuel delivery systems...DI and traditional injection (which sprays the intake valve). Otherwise people have to have their intakes removed and get their valves blasted with walnut shells or scraped with special tools. It's a problem. And some people are also using an oil catch can to trap some oil before it enters the intake manifold.
But the fuel mileage increase is great, there haven't been many mechanical problems with the systems. I just wonder about the oil, because it does seems to get dirty quickly and I keep hearing that it's "tough" on the oil.
