Right oil for a 350k km Vulcan ?

[newbietrucker]

I purchased the truck a few years ago: I'm not a high mileage driver: got it at 311k and now, a few years later, only have 354k klicks on the odometer. Great truck, starts all the time in any weather, engine's got a good growl and, even with a couple bad sensors, passed its last emissions test with flying colours.

I was getting well over 600km highway, and almost 600km city, per tank when I bought the vehicle. I lost a bit when I replaced the broken cam sensor (the one behind the engine at the firewall), but it was still reasonable.

Now I'm barely getting over 500 on the highway and not even that in the city. I'm sure sensors (or to be more exact, lack of properly working sensors) have something to do with that, but...

I'm pretty sure it's been on 10W30 or 5W30 since I got it. Last month I insisted on 5W20 and the mileage went through the floor.

So, two things...

What would you suggest for a winter oil to get my mileage back where it belongs ? and can I add a quart of some really heavy oil (when there's room) to make up for the lighter oil that's in there now. I'm assuming that some of the reason the mileage is so poor is much increased blowby.


Thanks,

Pat

(oh and is there anybody that makes an EGR tube for a Ranger 3.0 without the ridiculous price tag that Ford charges for a piece of bent Y-pipe ? I figger if I can find something not too unreasonable I can get all the sensors fixed and fly through e-testing in April)

 

[exbass94]

Thicker oils usually decrease gas mileage, not the other way around. I doubt the oil has anything to do with your mileage drop. If you want to use something thicker, I would go no thicker than a 5w30. You can add some thicker oil to the 5w20 in the meantime.

 

[RonD]

I would agree with poster on the 5w20 being the wrong choice and causing the MPG drop.
High mile engine will be having to deal with more oil in the cylinders, from older rings and leaking intake valve guide seals, this reduces overall power so your foot is closer to the floor to maintain speed, so MPG goes down.
Changing to the "thinner" oil just adds to that decrease in power by allowing more oil to get into cylinders.

Yes, next time switch back to original 5w30, or even a 10w40.

Blow-by is present on all engines, as the compression rings get older they can't hold compression as well so blow-by increases, this wouldn't be effected by the viscosity of the oil, BUT some oil on the cylinder walls is vaporized by the high temp blow-by, this is normal as well, but increased blow-by means increased oil vapor.
So PCV valve pulls in more oil vapor to be burned.
Some cheaper brands of oils vaporized easier, so in that respect viscosity could be a factor.

At this time I would pull the spark plugs and check them for carbon/oil fouling, clean or replace as your wallet dictates.

This burning of oil also effects O2 sensors, recommend change time on these is 70,000 miles so.................O2 sensors tend to "go rich" as they get older, so while they won't turn on the CEL because technically they are working, they are telling computer the engine is running lean so computer runs engine richer than needed, and MPG goes down.

 

[Dune Runner]

I would go to Pennzoil HM 10w30 or Valvoline Max Life 10w30. I would replace the o2 sensor also. Running thin oil might have been fine in a newer engine but not a high miler.

 

[Rearanger]

Checked your compression lately?

 

[kimcrwbr1]

How old is the cat and oxy sensor/s. How often do you change the PCV you should change it with spark plugs as a habit. Think preventive maint first change all gear oils if you havent and a complete tuneup including PCV. Put some seafoam in the next couple of tanks after you change the fuel filter. It is a little over 200,000 miles the motor is still just a baby. Also check the timing chain it may be getting sloppy?