Back Spec oil weights.

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Toyota and Honda back spec'd oil wt to 0-5-20 several years ago. Doesn't CAFE have effect on a current model year or does CAFE go back several years from the present? If only the current year, why back spec oil weights.
 
Originally Posted By: Shannow
I've posted those rules before.

You could use the search function.


That doesn't help me. Refresh us. I've never had success doing that.
 
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Tig1, I'm with you. I'll go back through Shannow's old posts and see if I can find it or us.
 
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Oops, I give up. I forgot how many posts he has!
frown.gif
 
Originally Posted By: tig1
Toyota and Honda back spec'd oil wt to 0-5-20 several years ago. Doesn't CAFE have effect on a current model year or does CAFE go back several years from the present? If only the current year, why back spec oil weights.


I'm with tig on this one. That Acura oil chart confused me even more haha. 10W30-5W30 was the only spec at first,and said 20wts were "usable and acceptable". Now they all spec 20wts without the terms "usable and acceptable".

1. Did they figure out that 20wts control wear better?
2. Have oils excelled to the point that today's thin oils have a concoction of additives that don't rely on viscosity?
3. Is the movement to thinner oils purely CAFE?

Now I'm even more confused
shocked2.gif
 
Originally Posted By: aquariuscsm
Originally Posted By: tig1
Toyota and Honda back spec'd oil wt to 0-5-20 several years ago. Doesn't CAFE have effect on a current model year or does CAFE go back several years from the present? If only the current year, why back spec oil weights.


I'm with tig on this one. That Acura oil chart confused me even more haha. 10W30-5W30 was the only spec at first,and said 20wts were "usable and acceptable". Now they all spec 20wts without the terms "usable and acceptable".

1. Did they figure out that 20wts control wear better?
2. Have oils excelled to the point that today's thin oils have a concoction of additives that don't rely on viscosity?
3. Is the movement to thinner oils purely CAFE?

Now I'm even more confused
shocked2.gif



I believe it's CAFE

I'm fine running 5w and 10w30's in my Camry with no ill effects
 
It seems like I am hearing about more new vehicles are calling for 5-30 now.

I have run 5-30 in everything I have ever owned that called for 5-20 and no blown engines. A few I have run 5-40 in some and no problems either. 100reds of thousands of miles.
 
IIRC CAFE only matters for the current model year. As it is on average sold, I guess the definition of that would be most recent full model year?
 
Although I'm not literate on all the machinations of cafe credits, I agree, it seems kind of goofy to back spec oil recommendations if no monetary incentive is involved...or is there?

Here's a theory:
Since Toyota USA et al are separate entities within the corporate infrastructure they have their own set of rights, profits and liabilities to consider in determining their business model. Given that, at the dealer level profits could be increased if expenses are lowered. One way of doing that is to maximize bulk oil purchase to as few grades as possible.

To illustrate this, I requested an oil change with synthetic oil for my Yaris at the dealership back in 2015. They were prepared to put in 0W20 instead of the recommended 5W30. When asked why they claimed they only carry 0W20 synthetic.
 
Originally Posted By: Coprolite
IIRC CAFE only matters for the current model year. As it is on average sold, I guess the definition of that would be most recent full model year?


https://bobistheoilguy.com/forums/ubbthreads.php/topics/2658661/Re:_CAFE_has_Little_to_do_with#Post2658661

Quote:
What are CAFE credits?

Manufacturers can earn CAFE “credits” to offset deficiencies in their CAFE performances. Specifically, when the average fuel economy of either the passenger car or light truck fleet for a particular model year exceeds the established standard, the manufacturer earns credits. The amount of credit a manufacturer earns is determined by multiplying the tenths of a mile per gallon that the manufacturer exceeded the CAFE standard in that model year by the amount of vehicles they manufactured in that model year. These credits can be applied to any three consecutive model years immediately prior to or subsequent to the model year in which the credits are earned. The credits earned and applied to the model years prior to the model year for which the credits are earned are termed “carry back” credits, while those applied to model years subsequent to the model year in which the credits are earned are known as “carry forward” credits. Failure to exercise carry forward credits within the three years immediately following the year in which they are earned will result in the forfeiture of those credits. Credits cannot be passed between manufacturers or between fleets, e.g., from domestic passenger cars to light trucks.


So yes, they can get credit for backspeccing...

Nice try 'though tig1...
 
Mitsubishi has changed the oil recommendations on their 6B31 engine a few times. It started out with 5w-30, then changed to 5w-20 and then on to 0w-20 with no evidence that any changes were made inside the engine. The idea of back-spec oil recommendations on previous years though would certainly be confusing. If 5w-30 was good last year and this year it's not, I would expect a lot of questions. Ford has been going in the other direction with some of their EcoBoost engines.
 
Originally Posted By: callbay
It seems like I am hearing about more new vehicles are calling for 5-30 now.

I have run 5-30 in everything I have ever owned that called for 5-20 and no blown engines. A few I have run 5-40 in some and no problems either. 100reds of thousands of miles.


My sons 2017 GMC Yukon calls for 0-20 and his engine hasn't blown up either. I was wondering about back spec and why engine builders do that. Sometimes they back spec to 20 wt oils, sometimes they go from 20 wt to 30 wt.
 
Originally Posted By: SilverFusion2010
The reality is that for almost every street car you can dump in 5w-30 and change every 5-7k and the engine will outlast the rest of the vehicle.


And I have noticed the same with 20 wt oils. I noticed that in 1978 when I switched from 10-40 dino to M1 5-20 in a Slant 6 Dodge pickup engine. Still the same today as I have put about 400K on Ford engines using 0-20. But that still doesn't explain the back spec thing.
 
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