Benefits of a C6 Oil in a car that requires C5?

[jtay2024]

Morning all!

I was looking for oil for my Dads car last night. He has a 1.5 Ecoboost Fiesta ST. It comes with 200hp but his has been tuned to about 240hp now.

His oil spec is a Ford standard, of which most oils that meet it are C5 rated.

There are however some oils that meet C6 as well.

That got me thinking. Surely C6 oils would be a good upgrade choice for anyone who's cars expect C5?

This biggest difference is that C6 targets LSPI. Now to me, this could havr benefits in general to the chance of knock on high output small engine cars anyway? I'm wondering if there would be a way to test it? Like knock counts or something like that?

What are peoples thoughts?

 

[YZJB]

The best oil to run in the 1.5L Fiesta ST is a 5W-30 with Ford WSS-M2C961-A1 (API SP/SQ/ILSAC GF-6A/GF-7A).

Don’t run the recommended 5W-20.

Also, they switched from recommending a C5 for the 2022 model year, changing to an SP/GF-6A 5W-20 (WSS-M2C960-A1). But still, the 5W-20 is too thin, especially when tuned.

 

[ka9mnx]

Is this a diesel?

 

[factorytuned2012]

5w-30 euro oil

 

[jtay2024]

Is this a diesel?

It's a petrol.

 

[YZJB]

5w-30 euro oil

Agree a 5W-30 Euro is also good in these, just make sure it’s VW 504/507 approved as the 1.5 EcoBoost has a wet belt driven oil pump as does most VW 4cyl diesels, so you’d hope 507 has some compatibility tests for wet belts.

 

[SubieRubyRoo]

5w-30 euro oil

Pennzoil Euro L 5w30. It’s on the discount shelf at most WMs

 

[YZJB]

Pennzoil Euro L 5w30. It’s on the discount shelf at most WMs

Can’t get the 1.5L Fiesta ST in USA, so not relevant to the OP unfortunately.

 

[SubieRubyRoo]

Can’t get the 1.5L Fiesta ST in USA, so not relevant to the OP unfortunately.

You mean to tell me they don’t sell Pennzoil Euro oil in Europe?

OP may know it as Shell Helix Ultra ECT 5W-30

 

[jtay2024]

Thanks for the recommendations of the oils. I'll look into the use of 5w30.

With regards to the C5 vs C6 oils, I am trying to work out whether there would be a benefit in a car that requires only a C5 oil. My logic is that due to the fact that C6 oils are designed to stop LSPI in cars that struggle with that, it'd likely help to reduce knock (normal knock) in an engine that is highly boosted and likely pulls timing on hard pulls. Most cars these days are designed to constantly monitor for knock and advance timing as far as possible for efficiency so if the oil was a better design and much less likely to allow for knock then I'd have thought there would potentially be benefits.

 

[Jetronic]

Thanks for the recommendations of the oils. I'll look into the use of 5w30.

With regards to the C5 vs C6 oils, I am trying to work out whether there would be a benefit in a car that requires only a C5 oil. My logic is that due to the fact that C6 oils are designed to stop LSPI in cars that struggle with that, it'd likely help to reduce knock (normal knock) in an engine that is highly boosted and likely pulls timing on hard pulls. Most cars these days are designed to constantly monitor for knock and advance timing as far as possible for efficiency so if the oil was a better design and much less likely to allow for knock then I'd have thought there would potentially be benefits.

No, the mechanisms between "normal" knock and LSPI are different, it's also why retarding ignition timing prevents knock but not LSPI.

 

[YZJB]

Thanks for the recommendations of the oils. I'll look into the use of 5w30.

With regards to the C5 vs C6 oils, I am trying to work out whether there would be a benefit in a car that requires only a C5 oil. My logic is that due to the fact that C6 oils are designed to stop LSPI in cars that struggle with that, it'd likely help to reduce knock (normal knock) in an engine that is highly boosted and likely pulls timing on hard pulls. Most cars these days are designed to constantly monitor for knock and advance timing as far as possible for efficiency so if the oil was a better design and much less likely to allow for knock then I'd have thought there would potentially be benefits.

No downside to using C6 in a C5 application.