Factory recomended 5w-30 or back spec'd 5w-20?

[VK56VD]

My grandfather has a '96 Mercury Sable Wagon DOHC 24V V6. He has always used the factory spec 5w30 (Castrol GTX) in it for the last 120k miles. I know Ford spec'd their older vehicles to 5w-20.

Should he stick to the normal 5w30 or use 5w-20. With summer temperatures being high and humid in MD and this car being used for around town driving, while being fully loaded in the back with heavy tools, all the time, which is the best to use?

 

[shrooms]

5W20 can be used all year, so use it.

Is it a Duratec? If yes, they love the thinner stuff.

 

[bepperb]

If he's happy with what's working, use it. If he's excited about something new, try the 20. There will be no noticeable difference for the car.

 

[VK56VD]

Originally Posted By: shrooms
5W20 can be used all year, so use it.

Is it a Duratec? If yes, they love the thinner stuff.


Yes, it's the 24V Duratec, not the 12V Vulcan.

Better MPG with the thinner oil in this motor?

 

[ThirdeYe]

You can switch to 5W-20, no problem. My sister just got an Escort ZX-2 a year ago or so and as far as we know it always had 5w30 or 10w30. The sticker on the windshield when we got it said 5w30. I switched it to 5W-20 and it's been fine since, sounds exactly the same and hasn't burned anything. Different motor, I know, but it was one of the ones specified to go back to 5W-20 and just wanted to offer my anecdotal evidence.

 

[saberz]

If Ford recommended and back specced the vehicle, then by all means go for it. Ford doesn't horse around, they put research into the decision and should be fine.

 

[bradepb]

even though I am a believer in the 5w20 where recomended I would stick with what he has always used, what if he had an engine problem later not even caused by oil, but it would not look good and you will feel bad.

 

[CROWNVIC4LIFE]

Originally Posted By: Anies
If Ford recommended and back specced the vehicle, then by all means go for it. Ford doesn't horse around, they put research into the decision and should be fine.

+1

My 99 4.6 was back spec'd to 5w20 after using 5w30 for 90K miles...It worked out very well and consumption went from a half a quart to zero quart being used in 5K miles OCI's...That is using 5w20 Motorcraft Blend...I stayed that way till 200K miles till the car was totaled in a hurricane.

 

[JHZR2]

IMO, such back-speccing is the factory saying "our engine tolerances havent changed and 20wt oils have gotten better and better... we've seen no abnormal wear using them in our newest engines, so they are also fine for yours".

Id trust it, but I'd also verify by UOA versus a run on a 5w30. Not necessarily a trend-forming exercise, but it will shed insight.

 

[Eddie]

I'm a bit more conservative here and would stick to the 5w30 myself. I'm sure the 20 Wt would be fine though. Any icrease in mileage would probably never be measured for a daily driver.

 

[mechtech2]

Back in '96, 5-20s were not common or readily available.
Of course they were not heavily recommended.

Being older and with warm weather, I'd use the 5-30 in that car. But in winter, you would benefit from the 5-20.

 

[Fordiesel69]

I myself would use 5w30 being it is higher mileage. However I would have no problems using 5w-20 if the need arose. You will get mixed opinions. Truth is, the difference is not noticable and wear will not be noticable between the two. The oil technology itself will determine wear numbers slightly.

 

[Steve S]

Originally Posted By: JHZR2
IMO, such back-speccing is the factory saying "our engine tolerances havent changed and 20wt oils have gotten better and better... we've seen no abnormal wear using them in our newest engines, so they are also fine for yours".

Id trust it, but I'd also verify by UOA versus a run on a 5w30. Not necessarily a trend-forming exercise, but it will shed insight.
Clearances!!! Tolerances are the allowed variances of the clearances.

 

[fdcg27]

I've used 5W-20 in our Vulcan.
Different engine, I know.
If Ford says that the 5W-20 is okay, I'm sure it is.
You could do what one of the pro techs said above, and use 5w30 in warmer months, with the 5W-20 for colder months.
You could probably use either year 'round and not notice any difference.

 

[Bill in Utah]

Either. It will not matter in ANY way. I ran 5w30 and 10w30 in my Taurus and while I had "issues" with the engine a few times, oil was not the cause of them.

That engine will run fine on any oil.

Bill

 

[Nickdfresh]

My father's 99' Sable with the 24v engine seemed to burn more 5W-20 when I tried it. I've gone back to Valvoline MaxLife 5w30 and it just doesn't use it much. He only does like 3000-4000 miles a year. Other than that, 5W-20 ran well in that car as far as I can tell...

 

[AuthorEditor]

My thought process is if it has run great on 5w30 all this time than it is doubtful you'll notice a gain or even a change switching to 5W-20. That engine was designed for 5w30 in the first place. Plus, today's 5w30 is bound to be better than the oils available in 1996, so you really can't go wrong. The switch to 5W-20 appears to be mainly to gain a little bit extra mpg for the fleet, and I suspect the back specing was just to keep things really simple for Ford dealers and also to get Ford owners used to the stuff. Sure, Ford did a lot of testing and found that 5W-20 will preserve an engine for the life of the warranty. That's all they care about. I'm not convinced that there is any real benefit.

 

[VK56VD]

Wow, nice!

 

[CaspianM]

With 120k miles on the motor 20 might be borderline thin or may not be. It all depends on the state of the engine. If it uses oil then I would stick with 30 weight on the upper range. I would consider a good synthetic 0w30 instead.

 

[4ever4d]

I am going to the 5-20 syn blend in my 96 4.6 Grand Marquis next oc getting harder to find the 5-30 at least it is for me.