5w30 oil making me run rough?

[mrpeepers]

Ok i just recently changed my 1992 s13 oil with full synthetic 5w30 and it has been running rough and mainly idling rough on cold starts. I check the oil levels and the gas already seems fouled with oil. just changed my O2 sensor and i know the cats are fouled. Before this, the car had one issue of over heat due to a leaky water pump, but the car was running fine for a few solid months after that. It is just recently that i switched to 5w30 from 10w30. Could my gas have been thinning my oil? Could the overheat incident loosened some seals? appreciate any feedback

[Yoshi]

I check the oil levels and the gas already seems fouled with oil.

Could you elaborate a bit on what u mean by this?

[aznpoopy]

i assume you mean your oil is being diluted with gas (not the other way around)

you may have an injector issue or other fuel related issue. check for stuck injector / bad injector wiring / bad o-rings.

[smelly240]

check your vac lines - and make sure u didnt knock off a plug... lots of people do that when they change their oil...

[unicoladron]

there's probably no need to switch to synthetic oil if you have a KA with 100,000+ miles. i'm assuming this is not an SR.

[mrpeepers]

THe oil is at the correct fuel level, a little bit below H actually. I meant fouled by gas in the way that old motor oil is fouled by gas.

Car is a KA. I will check my vac lines, but im not too sure about how to check injectors. I thought that synthetic was good for high mileage engines?

Edit: I just installed a 300zx fuel filter

[gotta240]

unless you are on a FRESH, and i mean fresh motor..

GET THAT FUCKING OIL OUT OF YOUR MOTOR.

If your ka has over 100k, do two things.

1. switch to regular oil(i prefer castrol)
2. try 10-40. See how that works

[mrpeepers]

ok ill change the oil asap... but can someone explain why...i never came across why synthetic was bad past 100k

[crazyc]

synthetic oil burns quickly if it gets too hot, and you stated you had over heating problems before so yeah some of the seals could be damaged

[mrpeepers]

As it is the engine temp is normal, just below middle line. The over heat issue was about 2.5 years ago and since then the car ran great on 10w30 Maxlife synthetic. It is just recently with the addition of a 300zx fuel filter, New O2 sensor (which i bet quickly fouled), and the 5w30 synthetic oil that that car is running rough. I have come to the conclusion that i will go back to 10w30 synthetic due to the fact that the over heat issue may have caused leaks. Ill let you guys know what happens

edit: The engine is probably around 100k, it was rebuilt and i think synthetics were being used at around 80k

[Bushido]

synthetic has also been said to dry out seals on an engine that has been run its whole life on conventional oil

[tiresmokes13]

Change the oil
i have always used mobil conventional non synthetic 10w-40

[S14DB]

Mobil makes non Syth. All Mobil 1 is Synth.

I have never seen so many old wives tails...

http://www.mobiloil.com/USA-English/MotorOil/Synthetics/Myths.aspx

and look, they make high millage synth too...

http://www.mobiloil.com/USA-English/MotorOil/Oils/Mobil_1_Extended_Performance.aspx

people amaze me sometimes...

[mrpeepers]

It said i could use 5w30 and 10w30 on the FSM so why not? ill give regular oil a try

[S14DB]

You have a fuel problem not an oil one. Your oil choice was fine. you have another problem.

[Forge_55b]

if its not a leak in the fuel system you might have a bad spark, and thus fuel going into a cylinder not burning and just flooding up ur oil maybe? not a whole lot you need to check but if you don't know what ur looking at, time to call a professional or get a factory service manual and start reading

[brokeAs240sx]

It isn't the synthetic oil & ur oil weight is still w/in factory guidelines (unless you are in some crazy extreme weather).

As for all the "over 100k don't use syn oil etc" - if your car breaks because of using syn oil, you got other problems... I also autox it on syn oil & syn blend. I find that the oil stays better (at least "feels" better from my butt dyno) than conventional dino oil.

I've used synthetic oil in my ~160k KA (it was about 130k or so when I started) for the past 4-5 years w/o a problem. I even switch back & forth trying different combinations/weights.

My car had a couple problems, but none of them were related to the oil I used, haha.

[gotta240]

i disagree with that oil weight strongly.

Those factory specs are like all other specs- MEANT FOR NEW/GREAT CONDITION motor.

Your motor sounds to be over 100k. Try 10-40. MAYBE 10-30, but i'd prefer not to. Like stated above, you MAY have other problems...but start with oil choice in MY OPINION.

[heychris]

Synthetic oil..because of it's higher flow properties (which is why it feels better to the butt dyno) can flow accross the piston rings in a high mileage engine. Many higher performance oil makers (Red Line etc) recommend using conventional oil beyond 60K miles. I would try switching back to where you were to see if that eliminates the problem, if not look to the fueling gods...Good luck!

[S14DB]

Synthetic oil..because of it's higher flow properties (which is why it feels better to the butt dyno) can flow accross the piston rings in a high mileage engine. Many higher performance oil makers (Red Line etc) recommend using conventional oil beyond 60K miles. I would try switching back to where you were to see if that eliminates the problem, if not look to the fueling gods...Good luck!

Higher Flow? Viscosity is the same with synth or dyno at the same weight. The synth has less friction at the same weight but the thickness is the same.

[Chrischeezer]

synthetic oil burns quickly if it gets too hot, and you stated you had over heating problems before so yeah some of the seals could be damaged
so wrong,
why do u think synthetic oil was invented? cuz it's physical properties surpass conventional oil by far.
but dont worry i still break my motors in with some crappy castol for a few thousand miles


your problem isnt with your oil, u might have a leaky injector.
but i would change to a differnt weight, keep synthetic, just go heavier

[cruque]

Hi originaly from factory the KA takes 5w-30 but that's starting from 0 miles and keeping good oil changes.If you just got a 100k KA and you put 5w-30 most likely is gonna smoke.My KA is 125k I use mobil 1 synthetic 15w-50 and it's all good.Im prity sure your problem does'nt have to do anything with fuel delivery most likely is spark or vacum.

[tiresmokes13]

Mobil makes non Syth. All Mobil 1 is Synth.

I have never seen so many old wives tails...

http://www.mobiloil.com/USA-English/MotorOil/Synthetics/Myths.aspx

and look, they make high millage synth too...

http://www.mobiloil.com/USA-English/MotorOil/Oils/Mobil_1_Extended_Performance.aspx

people amaze me sometimes...


http://www.mobiloil.com/USA-English/MotorOil/Oils/Mobil_Clean_5000.aspx

My mistake Yes Mobil.

[Forge_55b]

going seriously off topic, and if you think going from synthetic back to conventional is going to magically fix his engine seals after they may already be bad prolly isn't going to work but besides that why the hell would his oil seals being bad make the running oil full of gas? would it usually end up with burning oil and blue smoke out the tailpipe?

[backroadtouge]

this is madness

i use 10-30 valvoline heavyduty syn for over a year after switching from penzoil platinum which i ran for 2 years. im still lost on this whole over 100k dont use syn. 138k today on my KA. car runs even better on the valvoline. fix injectors and enjoy the syn

[S14DB]

NO MORE OIL TALK!

His problem is he's running rich.

[infinitexsound]

check ur sparkplugs... see how each cylinder is running.. start from there...

[mrpeepers]

ya sooo besides all the oil talk i think i am gonna pull miy plugs and injectors to see whats going on there. Ill start with the spark plugs first

[mrpeepers]

Ive been searching all day for info on bad injectors. I have found every thing except a visual inspection.

Can anyone enlighten me as to what i am looking for when i pull the injector? I know to look for O ring integrity, but what about the nozzle? Is there anyway to check spray pattern? Oh i learned that ka24e injector does not benefit from injector cleaners significantly because of the design. Ill look around for the article

[aznpoopy]

leave the injectors in

crank the car for a bit. stop. pull the spark plugs. the cylinder that is wet as hell relative to the others will correspond to the injector that is stuck open.

[mrpeepers]

Ok just changed my spark plugs. plug 1 was good with a little burnt oil on the threads and it got worse through 4. Plug 4's threads were soaked in oil. I started the car and it idled fine, but i dont think i solved the problem. Ill check the injectors tomorrow

[mrpeepers]

hmm i remembered a while back when i was a car noob that i painted my valve cover, but i dont know if i tightened it back per FSM.... ill give this a try

[jilo]

make sure the injectors arent leaking - take the fuelrail off the engine but leave the fuel lines connected. turn the key to the on position (dont start the damn car) and see if the injectors leak.

[mrpeepers]

I retightened the valve cover today per FSM and found a bad ground so i changed that too. If it starts running rough again i will go with the injectors. Thanks everyone, i guess it wasnt the oil viscosity. Oh and when i pulled off the valve cover there was NO SLUDGE WEEEEEE!