Engine Oil 10w-40 or 5w-40?

[steve1001]

Gentlemen

Ecp and the like seem to be recommending 5W-40 for my 306 (X reg 2.0 HDI).

For the last 15 years I have used 10W-40 (B3).

I see the the 5W-40 is thinner in Winter for easier starting.

Will I do any harm using 5W-40, or should I stick to 10W-40, as per the Haynes manual?

Thanks

Steve

[Jonny81191]

Either will do just fine. The 5w40 is theoretically the better oil as it'll protect the engine more from cold starts, but the OE recommended oil is 10w40 and the engine was designed with this in mind.. Basically, there's not all that much difference.

[steve1001]

Either will do just fine. The 5w40 is theoretically the better oil as it'll protect the engine more from cold starts, but the OE recommended oil is 10w40 and the engine was designed with this in mind.. Basically, there's not all that much difference.

Thanks very much Jonny81191.

I'm still in 2 minds whether to go for 5w40 or not. As you say they recommend 10w40. And yeah, I can't see what harm it could do, and it does look like it may be better when cold; and will still be the same as a 10w40 when warmed up.

Anyone else had any experience with it, or opinion?

Steve

[bashbarnard]

10-40 will be fine. Its the spec they came outta factory with. Dont mess with it. Your probably over thinking it to be honest.

[Mattcheese31]

Lots of people run both, I use 10-40 myself as that's what was specced for the engine

[zx_volcane]

'ang about

Isn't there something along the lines of "use some kind of oil, all good, use another kind of oil and all leaks break loose" I forget the detail but I'm sure that is the general gist of it.

im sure both are fine

[steve1001]

I probably am over thinking this.
I blame it on Euro Car Parts. I entered in my Reg number this morning, and they shoved Petronas 5w40 in my face. The Petronas kind of hooked me in, as I've seen it on Formula 1 cars.
I'll stick with 10w40 as it is tried and tested.

[Mattcheese31]

'ang about

Isn't there something along the lines of "use some kind of oil, all good, use another kind of oil and all leaks break loose" I forget the detail but I'm sure that is the general gist of it.

im sure both are fine

iirc that was some full synth variety that I've heard Ruan bitching about before is it Fuchs?

[Anton]

Always used 5W40 Fully Synth in my Xud's and they've been fine, always ran great and quiet.

[Jonny81191]

I probably am over thinking this.
I blame it on Euro Car Parts. I entered in my Reg number this morning, and they shoved Petronas 5w40 in my face. The Petronas kind of hooked me in, as I've seen it on Formula 1 cars.
I'll stick with 10w40 as it is tried and tested.

http://www.upmpg.com/tech_articles/motoroil_viscosity/


This might help explain it a bit.

[Ruan]

'ang about

Isn't there something along the lines of "use some kind of oil, all good, use another kind of oil and all leaks break loose" I forget the detail but I'm sure that is the general gist of it.

im sure both are fine

iirc that was some full synth variety that I've heard Ruan bitching about before is it Fuchs?

Fuchs Titan Pro S was what caused chronic uncontrollable oil leaks on 3 XUDs - now could be that one batch, since 3 of us all bought it at the same time, from the same place, but all had the same issue.

[MY95]

Id go with whatever you can find cheapest/best for the money. Ive used both in my HDI this year, ran slightly quieter with 5W40 but no better performance/no real noticeable improvement in MPG.
Just bought some 5w40 Triple QX 5L from CP4L the other day for £10.99 delivered!

[Poodle]

As Jonny says, in a direct comparison 5w40 will be better, but sticking to the original 10w40 is fine if you're more comfortable with it. I doubt you'll notice the difference and the engine certainly won't complain.

[pro_steve]

I had the same at Euro this week, normally they recommend 10W40 but now they've changed it.
I've experimented around with it and I've tried 5W30 in the 2.0s, but I've decided I prefer to use 10W40 now.

[Jonny81191]

I had the same at Euro this week, normally they recommend 10W40 but now they've changed it.
I've experimented around with it and I've tried 5W30 in the 2.0s, but I've decided I prefer to use 10W40 now.

Interesting, what made you go for the 10w40?

[Paul_13]

10w-40 fully synthetic cause my xud to leak well bad. Don't use it imo

[Jonny81191]

But that's different, you're talking about using a fully synthetic oil, which has a lot more additives in it.

[Paul_13]

It was response to zx_volcane's post above mate, my phone goes spastic if I quote a post.

[Jonny81191]

It was response to zx_volcane's post above mate, my phone goes spastic if I quote a post.

I see. So we're saying the fully synth is what's causing leaks due to additives?

Ruan? was the Fuchs fully synth?

[cully]

ive just filled my XU10 new engine with 5-40 fully synthetic castrol edge not one leak ...............yet!

maybe your leaks are down to worn seals?

[Jonny81191]

Yeah, should have clarified. It'll be where the seals are bedded in using a part synthetic oil and then hit with fully synth.

^Speculation BTW, I don't know this for a fact.

[rd070707]

interesting this, I've always used 5w-40 fully synthetic total quartz and I must say I do have a few small leaks. Would the 10w-40 help reduce this?

[Jonny81191]

interesting this, I've always used 5w-40 fully synthetic total quartz and I must say I do have a few small leaks. Would the 10w-40 help reduce this?

Yeah, due to the viscosity when cold. But when hot it'll theoretically make no difference. Fully synth vs Semi synth I don't know.

[Paul_13]

All seals were new on the engine

[Ruan]

The Fuchs Titan Pro S stuff was a Fully Ester Synthetic 5w/40 which caused it to leak, I've since used Millers CFS, Aeroshell Diesel (lol) and towards the end I stuck on Gulf Competition 5w/40, all of which are Fully Ester Synthetics which didn't make the leak worse, had I have kept on with Titan Pro S, it'd have pissed all the oil all over the floor within minutes - it just eat the vacuum pump seals.

"Fully Synthetic" really means very little.

Whether it'll leak is all to do with the additives in the oil, which changes brand to brand - there also needs to be a distinction made between "Fully Synthetic" and "Fully Ester Synthetic" since they're two quite different things.

HDis I thought the factory recommended Total Quartz 9000 as the oil they were certified on... Which is a 5w/40 "Fully Synthetic".

The 5w/40 or "fully synthetic" doesn't really show the full picture anyway, that's merely the viscosity at two temperature points, and whether it's base stock is a certain proportion that came out the ground, or whether it's chains were made in a laboratory. It's easy to make an oil fit two temperature points, it's what happens to that oil when the oil is past those temperature points that really matters, especially if you're tuning an engine - the better the oil, the more stable it is at extremes of temperature and in Diesels how good those additives are at dealing with excessive fuel in the oil and screwing with the ability to protect the bearing surfaces with high concentrations of fuel in it.

[pro_steve]

I had the same at Euro this week, normally they recommend 10W40 but now they've changed it.
I've experimented around with it and I've tried 5W30 in the 2.0s, but I've decided I prefer to use 10W40 now.

Interesting, what made you go for the 10w40?

Well, it might just be in my head but I'm sure it's a little quieter with the 10W40 over the 5W30, and when running lots of boost thicker oil must help prevent the lifters from collapsing at the higher revs, I might try a back to back comparison and see if it actually makes a difference. 

I only tried the 5W30 because in one of the Peugeot manuals it said you get better MPG and performance due to the reduced viscosity, but I haven't noticed much of a difference if any. 

I did just read that if you have the wrong viscosity then it can drain out of the hydraulic tappets when the engines off, so using 10W over 5W could make sense to make it start up quieter?

[JTaylor2005]

I have used shell helix ultra the last 2 changes I have done. That's fully synthetic and I have no problems with leaks

[Ruan]

I had the same at Euro this week, normally they recommend 10W40 but now they've changed it.
I've experimented around with it and I've tried 5W30 in the 2.0s, but I've decided I prefer to use 10W40 now.

Interesting, what made you go for the 10w40?

Well, it might just be in my head but I'm sure it's a little quieter with the 10W40 over the 5W30, and when running lots of boost thicker oil must help prevent the lifters from collapsing at the higher revs, I might try a back to back comparison and see if it actually makes a difference. 

I only tried the 5W30 because in one of the Peugeot manuals it said you get better MPG and performance due to the reduced viscosity, but I haven't noticed much of a difference if any. 

I did just read that if you have the wrong viscosity then it can drain out of the hydraulic tappets when the engines off, so using 10W over 5W could make sense to make it start up quieter?

In my experience, it's not the lifters collapsing with high RPMs or boost... The same lifter design is used in the Renault F4 engines, i.e. Clio 172/182, which spin to well beyond 7000rpm and more in a tuned application...

The problem that IME happens would not be affected in the slightest by oil viscosity...

[bashbarnard]

Just to throw my 2p into the works. My old 1.9 i used to have id throw anything in and it was fine. And i mean anything. Used oil, 5-30 10 40 20-50 sometimes even 0-20 whatever i got from work. It used to not care. The following 1.9 i had i put fully in first one i ever tuned. Oil leaks everywhere. That was patronus before they sponsored f1. 2.1 always had 10-40 semi comma stuff. Never had a single leak. In fact i think it was the cleanest xud id ever seen.

[Frosty]

I've always used 10w40 in both my xud and hdi and never had any issues