Oil weight....has damage been done?.

[Philz]

I let family member use my 96 ltd for a few years finding they did oil changes using 10w 40 racking up over 20 thousand mile on that weight.
I got truck back a couple months ago , did the timing belt change etc lots of $$ spent.
its running great but gas millage sucks Im losing 2 miles a gallon thanks to oil used in my absence

Is it safe to go back to 10w 30 ?

Thanks

Phil-

 

[nissanh]

I go between 10-30 or 10-40 and see no difference in the gas mileage.

 

[LittleCaesar]

It is safe, though blaming the big loss on using 10w-40 may not have much merit.

I'd look at older O2 sensors, dirty MAF, old wires and plugs, dirty fuel filter and injectors, etc. as starting possibilities for your loss.

 

[Philz]

I go between 10-30 or 10-40 and see no difference in the gas mileage.

Ive come across so many posting that thicker oil negatively effect gas mile.
If that's not the case with 3.4 great news...well sort of.
hmm Maybe my o2 sensor with 195 thous mile is culprit

 

[Philz]

It is safe, though blaming the big loss on using 10w-40 may not have much merit.

I'd look at older O2 sensors, dirty MAF, old wires and plugs, dirty fuel filter and injectors, etc. as starting possibilities for your loss.

yeah I have all bases covered except for o2 sensor,
o2 must be the culprit, its got miles on it but no code as of yet

 

[LittleCaesar]

O2 sensors can be a culprit. If you don't know what gas was used, I'd definitely recommend an injection cleaner such as Seafoam in the rank or Royal Purple injection cleaner before the next oil change.

 

[Philz]

O2 sensors can be a culprit. If you don't know what gas was used, I'd definitely recommend an injection cleaner such as Seafoam in the rank or Royal Purple injection cleaner before the next oil change.

Thanks for feedback!
Yeah not sure what gas was used that could be the problem.
I will pick up some Royal Purple tomorrow give it a go.

I know f,sure they used my preferred oil brand "Mobile 1 high millage" every 4000 - 5000 thousand miles so good on that front.
If no damage is done with 10w 40 I will stick with it.

 

[SilverRidgeRunner1]

It seem a bit off topic but rather interesting and related kinda. When Toyota released the NEW 2007 Tundra w/ the 5.7 V/8 a Service bulletin was dropped down to us only use 0w-20 oil only when servicing these trucks. Couple of reason were because of the new timing chain systems used in this truck at the time it was a new design which required a different weight of oil than normal 5w30. The other reason for this change as well is Toyota advised that the MPG that was posted on the window sticker could only be achieved by using 0w-20. So does oil weight/viscosity matter for mpg could be according to Toyota at the time for that vehicle has to be some truth to it. Just thought it was a interesting subject that could be related to this.

 

[jgue467]

... The other reason for this change as well is Toyota advised that the MPG that was posted on the window sticker could only be achieved by using 0w-20. So does oil weight/viscosity matter for mpg could be according to Toyota at the time for that vehicle has to be some truth to it. Just thought it was a interesting subject that could be related to this.

Yeah using the correct viscosity matters for both cold start up protection, general operating protection and fuel efficiency. I use shell's t6 5-40 and get 18.9 combined, not bad for a 15 yr old vehicle with over a quarter million miles. :cowboy:

 

[Philz]

Stopped by dealer today spoke with lead mechanic touched base on oil weight.
He highly recommended I stick with 10w40 due to high miles & summer time heat in are area - Va Beach/Outer banks NC

This winters been so cold 5w40 looks like all around perfect fit.
To bad my preferred oil brand doesn't have that weight in their lineup.

 

[LittleCaesar]

I live in New Bern and in DC. It doesn't get all that hot to warrant using 10w-40. If you lived in Death Valley CA, then maybe. I use 10w-30 with no issues.

Will it hurt anything? Nothing but gas mileage during the winter only due to taking a little longer to warm up. As long as your commute isn't under 3 miles, no harm done.

 

[Philz]

I live in New Bern and in DC. It doesn't get all that hot to warrant using 10w-40. If you lived in Death Valley CA, then maybe. I use 10w-30 with no issues.

Will it hurt anything? Nothing but gas mileage during the winter only due to taking a little longer to warm up. As long as your commute isn't under 3 miles, no harm done.

I think my surf racks , surf stickers , OBX sticker & larger tires gave tech hint that I do lots of beach driving influencing his oil recommendation.
90deg+ air temps driving in sand gets pretty hot.

I picked up some royal purple going to drop in tank next fill up.
I'm also replacing both o2 sensors , Purchased Densos.

Hopefully problem solved

 

[Philz]

I live in New Bern and in DC. It doesn't get all that hot to warrant using 10w-40. If you lived in Death Valley CA, then maybe. I use 10w-30 with no issues.

Will it hurt anything? Nothing but gas mileage during the winter only due to taking a little longer to warm up. As long as your commute isn't under 3 miles, no harm done.

Speaking of warm up,
Ive noticed morning warm ups to be a little ruff....feels like miss taking place & rich gas smell is present from exhaust.
After 5 min all smooths out.

New plugs , New coil packs , plug wires , fuel filter , Air filter & cleaned maf ...heck Ive done lots of work last couple month.

Ive been stuck on oil grade , o2 being culprit for mileage issue but could it be failing injector?

.

 

[96LTDrus]

Speaking of warm up,
Ive noticed morning warm ups to be a little ruff....feels like miss taking place & rich gas smell is present from exhaust.
After 5 min all smooths out.

New plugs , New coil packs , plug wires , fuel filter , Air filter & cleaned maf ...heck Ive done lots of work last couple month.

Ive been stuck on oil grade , o2 being culprit for mileage issue but could it be failing injector?

.

A failing injector is definitely a possibility... you can check by testing for resistance across the injector plug, if one is significantly different than the others than you know there could be something wrong with it (corroded solenoid wires).

Other idea is IAC valve cleaning.

O2 sensors are certainly not to be discounted either.

 

[19963.4lsr5]

A dirty injector is also a failing injector that a meter will never find.

I'd recommend a double dose of techtron in 1/2 tank and run it to the low light then fill up with 1 bottle and run to low light.

What is your fuel pressure? It be worth checking it when it's running poor during warmup.

 

[gamefreakgc]

Ok guys.

FSM states to use 5w-30 if experiencing temperatures below freezing. If not below 30 but over 100, use 10w-30.

That being said, you could put gear oil in these engines and they would still run. Or keep the same oil for 20k miles, it'll still run. It's not gonna hurt anything.

 

[pluton]

Ok guys.

FSM states to use 5w-30 if experiencing temperatures below freezing. If not below 30 but over 100, use 10w-30.

That being said, you could put gear oil in these engines and they would still run. Or keep the same oil for 20k miles, it'll still run. It's not gonna hurt anything.

Agree, but doesn't the FSM/Owner's Manual says 5W-30 below 0ºF, not freezing(32ºF)?

The most important thing is that the engine has oil in it, the secondary thing is exactly what spec oil.

 

[white_n_slow]

Here's a thought: Do they use winter blend gas in VA Beach? If so, it's probably just the gas that's costing you 2mpg. Not uncommon at all to see MPG's drop by 1 or 2 in the winter time.

 

[SpidermanGeek]

I just bought my rig in January and it's been absolutely cold. I'm getting under 12MPG average at the moment.

Previous Owner kept up with maintenance, but I think the Toy is due for a serious tune-up.

With that said, I plan to use Mobil1 5W30 at 5K intervals since it's the recommended weight for my area and it's also what I use in my Matrix. It will make things much easier.

 

[LeeMajors]

I just bought my rig in January and it's been absolutely cold. I'm getting under 12MPG average at the moment.

Previous Owner kept up with maintenance, but I think the Toy is due for a serious tune-up.

With that said, I plan to use Mobil1 5W30 at 5K intervals since it's the recommended weight for my area and it's also what I use in my Matrix. It will make things much easier.

Man, you guys with <12mpg trucks give me the willies.

I noticed a drop when it got 'cold' here in SC from about 21 to 19 or so. Of course, I drive like a grandmother and log lots of highway miles on my commute.

I'm hoping it'll go back up in the Summer though.

_______

This may be a stupid question, but I'm considering switching to a heavier weight/high mileage oil since it is hot as balls in SC in the summer time, then maybe moving back to the thinner weight in the winter. I've never switched oil weights before, usually using the recommended value.

Any downsides to this? MPG take a big hit on that one? Or would I even be fine with the thicker oil year-round? It rarely gets below 20 or so here.

What about switching to 0w-20 or 30, as is standard in all newer Toyotas?