LexChamp

95 LS 174,000

Recently switch to Mobil 1 10-W40 Synthetic Oil. I’ve had the car several months and do not know what type of oil was used before. The first couple of months I had the car I never felt the car hesitate after a stop. After changing the oil, a few days later, I noticed the car has been hesitating. Sometimes after a stop, but now is doing it more often, practically every time I start the car and begin driving. The hesitation comes after pressing the gas; the car hesitates, than makes a big jump, than it goes as normal. The hesitation mostly comes when putting the car in drive and driving.

Has this has anything to do with the SYNTHETIC OIL. I am thinking of going back to what the manual recommends, 5W 30. Any suggestions will be appreciated.

sonyman

Oil alone will not cause a hesitation. There is no way. You are confusing cause with coincidence. On a side note, why are you running a 40-weight oil? The engine specifies either 10W30 or 5W30, depending on the climate.

LexChamp

You might be right, about cause with coincidence. Like I said the car had been running fine before the oil was changed. Someone in another forum mentioned if the throttle bodies had been cleaned? Could this be a reason ?
Why 10 W 40, actually a mechanic recomeded this oil because the size of the engine. I know, it makes no sence now that I think about it. I already had several people suggest to change to Synthetic 5W 30 or 10 W 30 as you suggested as well. Thanks

sonyman

Your mechanic sounds somewhat unintelligent to suggest a particular weight of oil because of an engine's size. If you just cleaned your throttle body, that could have an effect, or even just for other reasons. The throttle plate could be sticking, or there could be an issue with the throttle position sensor.

PureDrifter

iTrader: (10)

go and switch to 5w-30, then go and reset ur ECU by pulling the neg. battery cable for a couple mins OR puling the EFI fuse.

alsalih

First, it’s not a good idea to switch to synthetic at such high mileage as you will likely deal with leaks that the lower viscosity of the oil will seep through, switch back! This leads me to believe that the hesitation you’re experiencing is in fact related to the synthetic oil. How?? I would be willing to bet that the synthetic oil has started to leak around the sparkplug seals and is in fact shorting the sparkplugs and leading to the noted hesitation. Remove the sparkplug boots on top of the plugs and look inside to see if you find oil inside.

dario

Well at that high mileage it is not good to go to synthetic oil if it has never been used before. The car might start getting a lof of leaks due to switching oil but that has nothing to do with hesitation. My suggestions:

Seems like your car is misfiring so check:

1) cables
2)spark plugs and
3)maybe you have a bad fuel injector.

sonyman

HIGHLY unlikely. The sparkplug wire boots fit with an airtight seal around the spark plugs.

alsalih

Sonyman, I’m not talking about the sparkplug wire boots, I’m referring to the spark plug seal that seals between the valve cover and the sparkplug. If you remove your valve cover you’ll see what I’m talking about.

PureDrifter

iTrader: (10)

go take the plug wires out and see if there is oil there, if there is it means the seals are failing.

its relatively unlikely that ur going to bust a seal running 10w40 synthetic, 5w MAYBE but ud be safe with 10w.

LexChamp

95 LS 174,000

I changed my oil today back to Mobil 5W 30 (Non Synthetic) I drove it around the block and it did not hesitate or misfired. I did not get a change to drive it a few blocks. Tomorrow, I will drive it for a while and post the results. Furthermore, I will also check the wires in the next couple of days to check if there is oil in the plugs. I’m going to have to change the plugs and wires in the near future anyway.

Thanks to all who responded.

LexChamp

95 LS 174,000

I drove the car today for a while and I noticed a big difference since I went back to the 5W 30 (Non Synthetic Oil) There were a few hesitations but not as many as before. The car is definitely running a lot better, with far less misfires. I honestly feel the Synthetic Oil had a lot do with the hesitation and misfire and overall performance of the vehicle.

Bill Dowd

Using mobil one will not cause a car to hesitate you might have someone check the air mass flow box this sound like a possible cause. The mass flow box is right next to your air filter don't mess with it is is very expensive have the lexus dealer or your own auto shop man take a look at it. I recently found that a company now makes a mass flow meter cleaner that is now on the market I found it at pep boys it is easy to use possible could help. Again don't put your hands inside the air flow meter there is a sensing wire it't very small and if broken expect $500-800 repair bill. Also have your auto shop mand check the intake for carbon build up this is also a problem seen in the lexus after 75,000 miles. Happy motoring!!!!

Heepspo

It's been my experience that old plug wires often cause hesitation. I had it happen to an old car of mine and it ran like new after replacing the wires.

I've recommended it to others and it's fixed their hesitation problems, too. They thought I was this amazing car guru. ha. Far from it.

Also, I disagree with all the "don't use synthetic oil with high mileage" info. Synthetic oil is very important to an older, high mileage engine.

I actually started using synthetic on a Nissan Pathfinder with 167,000 miles and it actually made the existing leak a little better. Honest. The spots on the ground were noticeably fewer while the inside of my engine is SPOTLESS and clean all time. I have 206,000 miles on it now and it runs STRONG!

If you're sacrificing the longevity of your engine for the remote chance (and very unlikely/argueable non-existent chance) that your engine may develop a tiny leak, well... I don't know what to say to that.

Seems silly to me.

denverdog

so you changed back to non-synth oil and it did not misfire or hesitate? then the next day it did? you just proved it wasn't the synth oil.

another benefit of synth is the reduced strain on your ignition system in cold weather. when its 20 below zero, the synth still flows like its july.

mobil one forever!

do a search on seafoam to generally clean out your engine.