10/40 oil is OK vs 5/30

[sirgerman]

I been arguing in the Saturn forum about using in 10/40 oil in my Saturn sl2 with 161000 miles on , I use 10/40w because that the only thing that slow down oil consumption , one guy commented that ;

Using 10w-40 dino oil is not going to do anything but increase average piston temperature. Oil is the only coolant that the piston is directly exposed to and oil flow rate is what carries the heat energy away from the piston. Heat is what cooks the oil to carbon which is what blocks the rings. The higher the oil operating viscosity the lower the oil flow rate.



what do you guys make of that ?
should I go back to 5/30 oil ?
I have been using 10/40w for the last 40 000 miles without any problems

 

[aquariuscsm]

I think that guy is full of [censored]. 10W40 will not hurt your car in any shape or form.

 

[4ever4d]

To a degree he is correct. These are very intricate details of an oils function that is often made to be much more of an issue than necessary. There will not be enough difference to cause any problems IMO. Other issues of using a 10w-40 in place of a much better 5w-30 would be more prominent i would think.

 

[TFB1]

If you could measure it there may be ½*...

The cylinder walls are cooled by the flow of coolant circulating around them, most of the heat from the rings is transferred to the cylinder walls... I dare say having a bit thicker oil would mean more oil, so may actually give better cooling... Yeah there are going to be a bunch yelping on this one, but truth be known they can't disprove it...

 

[sirgerman]

keep in mind that the car has 161000 miles on it , i am not complaining about the car , also I been using 15/40 during summer too

 

[bvance554]

My old Saturn sl1 was bulletproof. It went through a lot of oil of course,but as long as there is oil in it it was happy. I would have felt confident running 20w-50 in it if u had to.

 

[armos]

I've used 10w40 on older engines, and many people do the same. I believe in doing that if it keeps oil pressure in spec. Some believe in using 40 grade even on a lower mile engine, in the belief that 30 was a CAFE compromise. 30 vs 40 is something that can certainly be debated to death, and it has. The same debate today has shifted to 20 vs 30.
But regardless of who is right, it's not going to hurt you to keep using 10w40. People have used 10w40 for very high miles, just like others do with 5w30. Given the consumption issue 10w40 is apparently working for your needs, so I'd stick with it.
The cooling argument sounds a bit strained, I doubt you could even measure a difference in that department.

 

[marc1]

Probably many on BITOG are not old enough to remember this. GM issued the famous 10w40 advisory in late 1983 declaring potential warranty invalidation simply because they were having issues with pre-ignition in their cars. GM fuels and lubricants division determined this pre-ignition to be caused in many cases from the polymers used to thicken the 10w40 oil of that era. The polymers would form deposits conducive to pre-ignition or in extreme cases cause piston ring sticking. Thus was born the "forbidden 10w40 in a GM" issue. Obviously many things are different today... the oil ring control / metalurgy is much better in modern engines and the polymer thickeners used on oils are also much different. Personally, I don't use 10w40 in my new cars / truck engines, I prefer to run as thin as recommended for reasons that have been discussed by others ad nauseum on BITOG. But I would not be afraid to if for some legitimate reason I had to. The initial reasons for the 1983 advisory are all in the past. There are new reasons to not use 10w40 today but they are not born from this 1983 advisory. I do use, as you can see in my signature, 10w40 in my older muscle car. I also savory the irony once per year that 10w40 is the mandated oil for my car as spelled out explicitly in the owner's manual... that would later be the bane of GM.

 

[Finn]

Sorry for stepping in but out of curiosity:

what sort of drop in hot oil pressure could one expect to see when switching from 10W-40 to "down" 5W-30?

I'm tempted to try 5W-30 in my MR2 which now runs on 10W-40 MaxLife.

 

[crazyoildude]

use hm oils.... 10w30- 5w30-

 

[jorton]

Originally Posted By: TFB1
If you could measure it there may be ½*...

The cylinder walls are cooled by the flow of coolant circulating around them, most of the heat from the rings is transferred to the cylinder walls... I dare say having a bit thicker oil would mean more oil, so may actually give better cooling... Yeah there are going to be a bunch yelping on this one, but truth be known they can't disprove it...


Does Saturn engine use piston squirters for cooling?

Try Mobil Super with sodium detergent add to clean rings.

 

[Garak]

Originally Posted By: marc1
GM fuels and lubricants division determined this pre-ignition to be caused in many cases from the polymers used to thicken the 10w40 oil of that era.


I'm old enough to remember it.

On our vehicles of the era (GM and otherwise), my dad stuck to 10w-30. He had a hatred of thicker oils, and relegated 40 grades to diesels only.

I've still got that bias against 10w-40. My view has always been that if one wants a 40 grade conventional, their are plenty of decent HDEO 15w-40s out there. Considering that 10w-40 oils aren't ILSAC rated anyway, a 15w-40 HDEO is virtually interchangeable. If one is going synthetic, there are 0w-40 and 5w-40 options, and 10w-40 synthetic is a waste.

 

[skyship]

Some engines do use thinner oils for additional cooling, but I don't think the engine concerned is one of them.
I would recommend a good quality 5/40 for an all year oil and a good dino is OK if you don't want to push the OCI limits. If you want to use a fairly long OCI, then a full synthetic would be better.
You could also look at one of the high mileage oils, but avoid the cheap 15/40 ones as they will increase the cold start wear factors.

 

[tgferg67]

If temperature is a concern, you can most likely overfill by 1/2 quart to lower oil temperatures/ring pack temperatures. The engine in my vehicle had a tsb on oil consumption(ring packs) and one of the countermeasures was to run an additional 1/2 quart of oil. It was noted this helps decrease ring pack temps.

 

[[RT] ProjUltraZ]

i think you could also try a blend of 5W-30 and 10W-40 to get a 35ish, but if you have a oil burning problem then it should be ok. i don't think it will create significantly more heat in the oil. overfilling may create more froth from the crankshaft tho, and decrease mpg further.

at 100C a 20 is around 9 and a 30 is around 10.5 but a 40 is around 14 or 15 visc so it's not a linear scale

 

[fdcg27]

We ran 10W-40 in everything all the time up until we bought our first 5W-30 spec machine in 1997.
My record for cold starts on 10W-40 is around -25F, which we see once every couple of decades here, on a '76 Civic CVCC that had spent the night outdoors. One of those rare times where full out on the manual choke knob was required.
Never had any evidence that the oil did any harm.
I run it now in my old e36, although according to the original OM recommendations, it's really too thin for the heat of summer.
Had a great UOA from the hottest part of the summer, so I'm not too concerned.
I'm using a 10W-40 in the Impreza to slow down leaks and consumption.
The BMW will be stored for the winter and the Impreza will go on a diet of either 10W-30 or 5W-30 Maxlife.
I have plenty of both stashed.
What I'm trying to say is that a 10W-40 won't hurt that little twin cam at all, especially in a climate as mild as that of most of Cali.
I'd give Maxlife a go and see whether it helps reduce consumption, for which the real Saturn engines are famous.

 

[CATERHAM]

Originally Posted By: sirgerman
I been arguing in the Saturn forum about using in 10/40 oil in my Saturn sl2 with 161000 miles on , I use 10/40w because that the only thing that slow down oil consumption , one guy commented that ;

Using 10w-40 dino oil is not going to do anything but increase average piston temperature. Oil is the only coolant that the piston is directly exposed to and oil flow rate is what carries the heat energy away from the piston. Heat is what cooks the oil to carbon which is what blocks the rings. The higher the oil operating viscosity the lower the oil flow rate.



what do you guys make of that ?
should I go back to 5/30 oil ?
I have been using 10/40w for the last 40 000 miles without any problems

He is correct but it doesn't address your issue of high oil consumption.
Running dino oil continuously is what has caused the carboning up of your oil control rings. Running a heavier than necessary oil may slow the oil consumption but it only masks the problem, it doesn't fix the problem and it will likely get worse if you continue to use a mineral oil.

To solve the problem you've got to clean and free up your rings.
Short of dropping the oil pan and removing the pistons and cleaning them you can try an over night engine soak with a product like kreem through the spark plug holes and then use a synthetic oil with a good reputation for cleaning like Pennzoil.
Stick with the synthetic oil for as long as you continue to own the car.

 

[fdcg27]

None of this is likely to help a Saturn engine.
All of this has been tried by members of the various Saturn forums and nothing really seems to help.
With a Saturn engine, as long as the owner keeps oil in it, it will run for a very long time.
High consumption is just a part of the location of the rings too high on the piston.
No oil will help with this.

 

[Noey]

I think the short answer to your question is that there's no problem going from 5-30 to 10-40. The difference might be more noticeable to your rings than it is to anything else, hence the slower rate of oil consumption. As a further FYI, I'm of the old school of 'If it ain't broke...', so the idea of addressing the cause of minor oil consumption increase in an otherwise well running engine w/161k on it is asking for trouble, esp. if thicker oil remediates the problem.

Your friend might be technically correct in much of what he says, but inaccurate in the real world of your particular engine. I wouldn't recommend using anything other than the OEM rec, but after 161k, you have to take into consideration the current state of the engine. I wouldn't go to a 20-50, but a 10-40 (or 15-40) is fine.

 

[sirgerman]

Originally Posted By: fdcg27
None of this is likely to help a Saturn engine.
All of this has been tried by members of the various Saturn forums and nothing really seems to help.
With a Saturn engine, as long as the owner keeps oil in it, it will run for a very long time.
High consumption is just a part of the location of the rings too high on the piston.
No oil will help with this.



I agree 100% on what you say but the only thing is help is 10/40w , if i use 5/30 i probably will be burning 2 q every 1000 miles