10W40 or... 10W50?!

[Ben Up North]

Doing an oil change soon (probably tomorrow), was looking at going to a 10W50 Penrite full synthetic, as my engine is running hot (unless the Mechanic I've got it booked into performs a miracle and actually figures out what's wrong and how to fix it)
Is that a good idea, if not, why not?

 

[Ratbag]

Too high a viscosity can cause extra wear at startup, and too much pressure on gaskets and other oil seals when at operating temperature.

Might be OK in an old and worn engine that's using oil and/or blowing smoke on acceleration.

Otherwise, 5W-40 FS is thin enough for startup down to about -20°C, and thick enough to keep the engine lubricated at 100°C (engine temperature) when the ambient temperatures are in the high 40s°C.

More is not necessarily better ...

 

[El_Freddo]

I’d be working out why the engine is running hot first.

No use changing the oil to find out you’re tearing the engine down for a HG job. Oil can end up with some coolant in it when the heads are removed if not done with the head lower than the engine.

Have a look at your owners manual for correct viscosity and ambient air temps. There is a table about oil viscoities to use in different conditions.

Cheers

Bennie

 

[Ratbag]

I’d be working out why the engine is running hot first.

No use changing the oil to find out you’re tearing the engine down for a HG job. Oil can end up with some coolant in it when the heads are removed if not done with the head lower than the engine.

Have a look at your owners manual for correct viscosity and ambient air temps. There is a table about oil viscoities to use in different conditions.

Cheers

Bennie

Agree about solving the source of the problem first, Bennie.

However, the owner's manual recommends 0W-20 FS! This oil is also fine for -20°C startup, but runs out of viscosity in the high 20s°C FFS! That's not even adequate in mid-winter here in Oz ...

The Russian OM recommends 5W-40 FS, IIRC.

 

[El_Freddo]

However, the owner's manual recommends 0W-20 FS! This oil is also fine for -20°C startup, but runs out of viscosity in the high 20s°C FFS! That's not even adequate in mid-winter here in Oz ...

The Russian OM recommends 5W-40 FS, IIRC.

I can’t say that I’ve seen an owner’s manual for such a late model vehicle, but with these vehicles being exported across the world I’d expect ambient air temps up to 50+ to be in that table.

If the AUDM has a set of oil viscosities listed that are not suitable for the local market’s conditions, then that’s pretty poor on the manufacturer’s part to say the least!

Cheers

Bennie

 

[Ratbag]

Neither have I, Bennie. I'm working on the basis that our SH still recommends 0W-20 FS (probably to conform to the flawed fuel economy parameters ... ), and the temperature table for 0W-20 FS is totally unsuitable for Australian conditions.

Our mechanic for the last 15-20 years also recommends 5W-40 Shell Helix Ultra FS for both our SG and SH. Both have the EJ253 donk.

 

[Ben Up North]

Additional reasoning why thinking about going to a 10W50:
The ambient temperature where I am drops below +20deg C on average about 20 days per year, and only after dark until about 9am at the latest. Up at my mates place on the tablelands, they get a few sub 10C nights a year, I don't think I need to go below a 10 anytime soon.
Given the increasing temperatures generally, currently the wet hits we're hovering around mid-high 30s with high to very high humidity every day. According to the mainstream modelling, temperatures as a whole are going to increase in northern australia.
Outside temperature & humidity seems to make an enourmous difference to my engine temperature, I reckon if I was in the sourthern states of Oz, I wouldn't think I had much of a problem at all, unless I was fanging it down the freeways every day.

 

[Ratbag]

Then use 5W-40 FS.

It is thin enough not to damage your engine at startup, and has sufficient viscosity at 45°+C (ambient) to protect your engine. 20W-50 is OK in buggered/very worn engines, but too thick at higher temperatures for an engine that's in reasonably good nick.

How many days do you get over 45°C up there in the high tropics? Practically none ... We get about 0-12 a year here, and we have a very typical Mediterranean climate here.

 

[Ben Up North]

How many days do you get over 45°C up there in the high tropics? Practically none ...

Last two years, a few, more than 5 I think (going from memory, haven't checked the data). It was pretty horrible with the humidity as well. They're going to become more a lot more frequent in the coming years according to modelling from the last few decades.

20W-50 is OK in buggered/very worn engines, but too thick at higher temperatures for an engine that's in reasonably good nick.

10W-50, not 20W-50.. I'm starting to believe that my engine is more than a bit on the buggered side.

 

[Ratbag]

I loathe the humidity in the tropics. Grew up in SE Queensland until about 26 y.o. Never acclimatized ...

I would only use a 10W-50 or 20W-50 oil if your engine is using more than about 0.5L per 1,000 kms or so. Otherwise a 50 weight oil will be too heavy.

 

[Ben Up North]

I would only use a 10W-50 or 20W-50 oil if your engine is using more than about 0.5L per 1,000 kms or so.

It hasn't used any oil since I had the heads done, about 5000 kms ago. (maybe 250ml going by the dipstick, I put almost a litre in it when it was approaching low and it went way over the dipstick full mark, so drained pretty much all of it out again, to get the dipstick reading about halfway between H & L)
So I guess I'll stick with 10W40...

 

[Ratbag]

You really are better off using a lighter weight - 5W-40 FS - as most engine wear occurs in the first 1-2 minutes after starting from cold, regardless of ambient temperature.

 

[Ben Up North]

You really are better off using a lighter weight - 5W-40 FS as most engine wear occurs in the first 1-2 minutes

This is where I start getting confused. some of the sites I've been looking at are saying 10W is better viscosity than 5W at low temperatures (suitable for down to -30Degrees???) Possibly a typo that's spread?

Edit: I must be Internet Jaded, I keep reading 5W-40 FS as 5W-40 FFS and thinking you're insulting me!

 

[Ratbag]

Ben, there's an awful lot of BS on the internet ... but I'm sure you already knew that!

Here's a simple explanation:

Motor Oil Viscosity Grades Explained in Layman's Terms

Motor oil viscosity grades and how they are selected. What do they mean and why is it important?

www.upmpg.com

I'm rather careful about keyboard bounce when typing 'FS' = Fully Synthetic.

FS oils are far tougher than mineral oils. A mineral oil has a lifespan of about 6 months or 10,000 kms in a working engine, whichever comes first. The Shell Helix Ultra in both our Foresters has done nearly 3 years and 10,000 in one and 20,000 in the other. In both, the oil still looks good (slight discolouration), feels like new and smells good (like new smell, no slightly burned smell).

Some modern European cars come with an oil analysis system. Some of these are showing that the FS oils are still fine at over 2 years and 23,000 US miles. Much better for the environment, and better to recycle.

 

[Ben Up North]

It will definitely be FS, FFS!
I'll put back the 10l of 10W50 I got them to hold for me (sale starts tomorrow) and get some 5W40 if I can, doesn't seem to be much in variety of that on special, certainly nowhere near as low as the 10W50 in price.

 

[El_Freddo]

Correct oil type is cheaper than new engines or rebuilds...

Cheers

Bennie

 

[Ben Up North]

On the topic of Oils..
and talking about E-types..
Would the full synthetics now available reduce the need to rev the engine that high once a month.?

 

[Ratbag]

@Ben Up North Unlikely. The carbon build up is from burning the fuel, not the oil.

 

[Ratbag]

It will definitely be FS, FFS!
I'll put back the 10l of 10W50 I got them to hold for me (sale starts tomorrow) and get some 5W40 if I can, doesn't seem to be much in variety of that on special, certainly nowhere near as low as the 10W50 in price.

Both Penrite and Shell sell a 5W-40 FS, but it isn't cheap! Around $10-13/litre in a 5 or 6 litre bottle.

When I first asked for it in 2012, Ross (our long-standing mechanic) said "Cripes, John, I only put that in Ferraris and the like." I replied "Then it should be just right in a Japanese engine." He agreed with that sentiment.

Don't get conned into 6 month/10,000 kms service intervals! Watch your oil use (of course), but also watch out for deterioration as I mentioned above. Check the oil when just changed to get an idea of what it looks, feels and smells like when new.

 

[Kevin]

Speaking of oils - my son found this today: