How Important is oil spec for a wet timing belt?

Joined
Jan 19, 2021
Messages
1
Location
Sheffield, UK
Hi guys,

I'm in the UK and own a 2017 Fiesta ST-Line Ecoboost 1.0 GTDI and have recently done my first oil change which was pretty rewarding but it came with first time jitters and paranoia (checking under the car and the dipsticks everyday for a week after lol). Around 3 months ago I just really had an overwhelming sense of really wanting to look after this car and for it to last as long as possible and became glued to BITOG!

Bear with me, but I'm just looking to maybe gather the opinion of some oil gurus...

This car should take 5w20 (WSS-M2948-B) and I thought to myself, does this spec really matter? It's been around for ages and it's quite annoying it's not listed as being superseded like many other Ford specs are. I've recently become paranoid about LSPI which WSS-M2C948-B oils haven't been clarified on whether they already tackle this problem (doubtful).

I went ahead and put in Mobil 1 AFE 0w20 (5w20 seems rare here in the UK) which seems pretty solid and meets all these:

Ford WSS-M2C947-B1
ILSAC GF-6A
FORD WSS-M2C962-A1
API SN PLUS

Yet again, the trend of paranoia continues (grab the tin foil hat for me would you guys ;-)) and I thought "crap, what if WSS-M2948-B has special soothing properties for the timing belt in oil system". So I drained that out and put some Shell Helix Ultra 5w20 in which does meet WSS-M2C948-B.

I actually dropped money on getting the details behind WSS-M2C948-B as it was bugging me and yes, there is an in-house belt in oil test. Looks like a belt is run in oil for 7 days at 150c and micro hardness, tensile strength, elongation and volume all must fall within a certain range. The only other things I can see that are making this spec so special is getting 0.7% better fuel economy (in-house test) over a specific reference oil.

So guys, what would you make of the belt stuff? I'd imagine all top rate oils would be fine, I can't imagine the Mobil 1 eating it to bits. As for the belt material, I think it's Hydrogenated Nitrile Rubber (HNBR) with some fibre glass cords in it.

Does anyone really think this spec is purely all based around fuel economy more than anything else and the belt in oil test is just nonsense and any oil would lubricate and not deteriorate it? I really just want a good LSPI preventing oil which I doubt any WSS-M2C948-B oil would.

Thanks for any help anyone can shed on this, go easy on me :)
 
Joined
Mar 13, 2013
Messages
1,128
Location
UK
Hi guys,

I'm in the UK and own a 2017 Fiesta ST-Line Ecoboost 1.0 GTDI and have recently done my first oil change which was pretty rewarding but it came with first time jitters and paranoia (checking under the car and the dipsticks everyday for a week after lol). Around 3 months ago I just really had an overwhelming sense of really wanting to look after this car and for it to last as long as possible and became glued to BITOG!

Bear with me, but I'm just looking to maybe gather the opinion of some oil gurus...

This car should take 5w20 (WSS-M2948-B) and I thought to myself, does this spec really matter? It's been around for ages and it's quite annoying it's not listed as being superseded like many other Ford specs are. I've recently become paranoid about LSPI which WSS-M2C948-B oils haven't been clarified on whether they already tackle this problem (doubtful).

I went ahead and put in Mobil 1 AFE 0w20 (5w20 seems rare here in the UK) which seems pretty solid and meets all these:

Ford WSS-M2C947-B1
ILSAC GF-6A
FORD WSS-M2C962-A1
API SN PLUS

Yet again, the trend of paranoia continues (grab the tin foil hat for me would you guys ;-)) and I thought "crap, what if WSS-M2948-B has special soothing properties for the timing belt in oil system". So I drained that out and put some Shell Helix Ultra 5w20 in which does meet WSS-M2C948-B.

I actually dropped money on getting the details behind WSS-M2C948-B as it was bugging me and yes, there is an in-house belt in oil test. Looks like a belt is run in oil for 7 days at 150c and micro hardness, tensile strength, elongation and volume all must fall within a certain range. The only other things I can see that are making this spec so special is getting 0.7% better fuel economy (in-house test) over a specific reference oil.

So guys, what would you make of the belt stuff? I'd imagine all top rate oils would be fine, I can't imagine the Mobil 1 eating it to bits. As for the belt material, I think it's Hydrogenated Nitrile Rubber (HNBR) with some fibre glass cords in it.

Does anyone really think this spec is purely all based around fuel economy more than anything else and the belt in oil test is just nonsense and any oil would lubricate and not deteriorate it? I really just want a good LSPI preventing oil which I doubt any WSS-M2C948-B oil would.

Thanks for any help anyone can shed on this, go easy on me :)
You appear to be worried about LSPI - do you have any evidence that the 1.0 EcoBoost suffers from this? I'm not aware that it does, hence no inclusion of LSPI in the 948-B spec, which is specifically for this engine.

Whilst the oil you have chosen is probably OK for this engine, I'll just point out that the 947-B and 962-A specifications are both built around API and ILSAC performance demands whereas the 948-B spec is built around ACEA as the EcoBoost engine is a European design. I assume your car is out of warranty now but this could play a role in any future 'goodwill' cover from Ford should anything go wrong.
 
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Back in Arizona. Finally
Welcome to the asylum !
3D0B147A-C87C-4A07-A016-5385671F9A74.gif
 
Joined
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It is a belt not made of metal, so the type of oil you use as long as its suitable for your climate is alright. It wont accelerate wear or anything.
 
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Mahzurrah!
Welcome! You clearly belong here, we obsess over nothing all day long.

PAO is known to be less friendly to seals, so from that I would wonder about a belt, you might want to avoid PAO for the belt bath. But I don't think there is anything special about the original Ford spec.
 
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Location
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Welcome! You clearly belong here, we obsess over nothing all day long.

PAO is known to be less friendly to seals, so from that I would wonder about a belt, you might want to avoid PAO for the belt bath. But I don't think there is anything special about the original Ford spec.
Too bad he didn't stay after the first post.
 
Joined
Aug 29, 2020
Messages
47
I have followed the 1.0 ecoboost very close on the internet and haven't seen one LSPI case of it as far as i know (Maybe one case but if i remember right that was the 1.5 ecoboost engine.)

I've have read of cases of the wet belt been disintegrated because of wrong non 948B spec oil being used but I've have no actual paper proof of evidence of that.

I've personally would have used the OEM spec oil from Castrol Magnatec 5W-20 E and called it a day.

But I'm of course open for new news about the 1.0 ecoboost of what the engine can tolerate or not and similar. LSPI and etc. I've have the chain version 1.0 ecoboost in my 2018 Ford Focus Mk4.

Very interesting topic and I've wish you best of luck JamesF0288 🙂
 
Last edited:

Zee09

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You appear to be worried about LSPI - do you have any evidence that the 1.0 EcoBoost suffers from this? I'm not aware that it does, hence no inclusion of LSPI in the 948-B spec, which is specifically for this engine.

Whilst the oil you have chosen is probably OK for this engine, I'll just point out that the 947-B and 962-A specifications are both built around API and ILSAC performance demands whereas the 948-B spec is built around ACEA as the EcoBoost engine is a European design. I assume your car is out of warranty now but this could play a role in any future 'goodwill' cover from Ford should anything go wrong.
You had me won over when you used "whilst"
 
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You should have no problems with the wet belt and the oil that's currently in there.

Having said that, I don't think LSPI is as big of a problem as they want us to think it is. No doubt it does happen in some operating environments and under certain conditions, just not something you'll experience every day on every drive cycle unless there is something majorly wrong.
 
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