15w40 vs 10w50 oil consumption

[FCD]

So i have a little Peugeot 106 with a tiny 1100cc Gas engine for my daily driver, it has a mind blowing 58 Hp and it burns some oil and i wanted to know, what oil do you think it would burns less oil with? a 15w40 or a 10w50 ? , it specs 10w40 which is what it is running now , i only paid 800 Bucks for it and i've been running it on some cheap brand of oil noone has ever heard of haha, i intend to get rid of it soon and get something better like a Diesel Ford Focus or Fiesta that i don't have to worry about breaking down every 2 months or so like this little Peugeot has, the good thing about it is that it gets 47 Mpg ( 5.0 L / 100km )

 

[The motor guy]

I didn't know they made a 10w50. I'm assuming it's a mild climate where you are? If so then I would use a 15w40 or a 20w50 oil would be better. The problem is the 10w50 has too far of a spread, so it's going to thin back down to like a 30 or 40 weight over time causing more burning.

 

[FCD]

to be honest i think that is not the case anymore , i've seen UOA's of various 10w60 oils such as Castrol and Valvoline and they hadn't sheared down to a 50 or 40

 

[SuperSalad]

The 10W-50 should burn less oil. Its thermal stability should be better than a 15W-40 and it being an SAE 50 should prevent more exchange between the crank and the cylinder than an SAE 40 would, thereby limiting the amount of oil getting into the combustion chamber.

 

[440Magnum]

People always guess that a thick oil will lower consumption, but there is at least one clear mechanism by which thicker oil can raise consumption (weak oil control rings leave more thick oil behind than thinner oil, but of course going too thin also raises consumption). My gut feeling is that an oil burning engine has a sort of "consumption vs. viscosity" curve that has a minimum oil consumption at some viscosity, and thicker OR thinner than that minimum will raise consumption. Where that minimum is depends on the engine, and trying to guess between two such similar oils is anybody's guess.

The 15w40 will be, for all intents and purposes, the same as the 10w40 currently in it. So I guess if it were mine I'd try thicker just to see which way it goes.

 

[Joe90_guy]

Noack volatility-wise, a 20W50 will be about 5%-ish, a 15W40 about 7%-ish and a 10W50 about 12%-ish. I would be very suspicious of any 10W50 semi-synthnetic meeting ACEA A3. If your 10W50 doesn't say A3 on the can, expect it be all mineral and have a very high Noack (17%-ish).
I'd go 20W50. It will also be your cheapest option.

 

[FCD]

i guess i will try 20w50 then ,that way i can use the same oil in both of my cars

 

[expat]

I would try giving it a piston soak.
But I'm not sure what you might have available to use in Spain to do this.
I'd also clean or replace the PCV valve.

Other than that, I would use a name brand oil.

 

[Jetronic]

Originally Posted By: Joe90_guy
Noack volatility-wise, a 20W50 will be about 5%-ish, a 15W40 about 7%-ish and a 10W50 about 12%-ish. I would be very suspicious of any 10W50 semi-synthnetic meeting ACEA A3. If your 10W50 doesn't say A3 on the can, expect it be all mineral and have a very high Noack (17%-ish).
I'd go 20W50. It will also be your cheapest option.


Talking about oil consumption: that engine the OP is referring to is a TU1 IIRC. Small brother of the TU5 engine. So which oils performed best in the tests on the TU5?

 

[Jetronic]

Originally Posted By: FordCapriDriver
i guess i will try 20w50 then ,that way i can use the same oil in both of my cars


no oil leack on the front right corner?

 

[Joe90_guy]

Originally Posted By: Jetronic
Originally Posted By: Joe90_guy
Noack volatility-wise, a 20W50 will be about 5%-ish, a 15W40 about 7%-ish and a 10W50 about 12%-ish. I would be very suspicious of any 10W50 semi-synthnetic meeting ACEA A3. If your 10W50 doesn't say A3 on the can, expect it be all mineral and have a very high Noack (17%-ish).
I'd go 20W50. It will also be your cheapest option.


Talking about oil consumption: that engine the OP is referring to is a TU1 IIRC. Small brother of the TU5 engine. So which oils performed best in the tests on the TU5?


I do know the answer but it's probably not wise if I answer the question directly (confidentiality and all that).

But I'm happy with my recommendation...

 

[Shannow]

Originally Posted By: MotoTribologist
The 10W-50 should burn less oil. Its thermal stability should be better than a 15W-40 and it being an SAE 50 should prevent more exchange between the crank and the cylinder than an SAE 40 would, thereby limiting the amount of oil getting into the combustion chamber.


Not sure what you mean by thermal stability, but the 10W50 will probably have the lighter basestock, more VII additives, lower flashpoint, ad s Joe90_guy points out higher NOACK.

10W50 would have an HTHS around 4.8 (for a synth) versus 4.3-4.4 for a dino 15W40, and that gap is likely to close in service.

I'd take the cheaper 15W40 over the 10W50...or as OP has suggested, just use the same oil in both cars, 20W50.

 

[SuperSalad]

Originally Posted By: Shannow
Originally Posted By: MotoTribologist
The 10W-50 should burn less oil. Its thermal stability should be better than a 15W-40 and it being an SAE 50 should prevent more exchange between the crank and the cylinder than an SAE 40 would, thereby limiting the amount of oil getting into the combustion chamber.


Not sure what you mean by thermal stability, but the 10W50 will probably have the lighter basestock, more VII additives, lower flashpoint, ad s Joe90_guy points out higher NOACK.

10W50 would have an HTHS around 4.8 (for a synth) versus 4.3-4.4 for a dino 15W40, and that gap is likely to close in service.

I'd take the cheaper 15W40 over the 10W50...or as OP has suggested, just use the same oil in both cars, 20W50.


By thermal stability I basically mean VI, since the change in viscosity over the temperature range should be less than a 15W-40 in most cases.

Those other properties you pointed out are generalities though and are not necessarily accurate for all brands. Volatility in particular can change drastically from one brand to another within the same vis range. If they rely solely on VI improver to build viscosity rather than base stock adjustment, then yes the volatility will be high, but if a high vis base fluid is used instead, then the volatility should decrease in general.

Since the only known difference in properties between the two grades are the viscosity at low and high temperature, the thicker 50 weight should provide a stronger (or at least thicker) oil film to resist blow-by and oil being forced into the chamber. Since the OP only asked about the difference between 15W-40 and 10W-50, those are all I commented on, but yeah a cheap 20W-50 will probably be better still and not break the bank. I just didn't want to expand on the original options laid out.

EDIT: When I say drastic I of course mean that in a relative sense since NOACK is a pretty tight spec to begin with, so you may have one at 5% and another at 9% for instance which I would consider "drastic" although in the grand scheme it isn't that big of a difference

 

[Popsy]

Back in the time (when I was young) and when 106 and AX with TU engines were all around the streets here in Brittany, some of my young and intrepid friends used Total Quartz 10W50 (supposedly at least group III, ACEA AB/B4, it also has a PSA certification of some sort).
There was an AX Sport (lively 1,3L engine!), an 1,1L AX, a 1,0L AX and a 1,5d 106. The AX sport was very fun, and I wish I could by one nowadays ! Others were more sluggish, but still like rolling coffins! We knew nothing about oil but 10W50 Total Quartz (or was it Elf competition 10W50? Don't remember, but it is probably the same stuff) was the oil of choice for these engines if you used to redline them a lot.

A friend of mine still has a 1,1L 106, I put semi-synth cheap 10W40 oil in it. It uses quite a lot of oil, but I don't feel 10W50 or 20W50 will do much good for her car, since her driving is all but sporty.

 

[FCD]

I might just keep running it on a Generic cheap brand of semi synthetic 10w40 until i sell it, i only paid 800 Euros for it and i'll change the oil before i sell it on and get something better

 

[Popsy]

How much oil does it burn?

I guess with Spanish summers you can go the 20W50 route.

Not comparable but I put Total Quartz 10W50 in a friend's Alfa 147 which is burning 1L/3000Km, and he says consumption has decrease to ~0,8L/3000Km now (vs previous 5W40 [censored] put by dealers and quick lube shops, lol)

Originally Posted By: Joe90_guy

I do know the answer but it's probably not wise if I answer the question directly (confidentiality and all that).


I'd very much like to know

Come'on, I very probably won't be able to buy these oils here....please please please!

 

[Olas]

Just fix it properly - Capri's are going up in price and not nly will you have the sense of satisfaction in knowing you did it *right*, but you save money on oil top ups and you increase the value of your investment.
It's not even a complex engine, so you have no excuses!

 

[Shannow]

Originally Posted By: Olas
Just fix it properly - Capri's are going up in price and not nly will you have the sense of satisfaction in knowing you did it *right*, but you save money on oil top ups and you increase the value of your investment.


Not sure that potential Capri buyers are going to check the oil consumption of his beater...

 

[Olas]

Depends if they want a shell for a YB build or something original for a resto project..

 

[Popsy]

I think the discussion was about the 106 in his sig.