1.5 carbon build up?

[TnTkr]

Maybe it's different service schedule in UK? In continental Europe it's 12 months and no recommendations about any additive.

[Bobcat]

Maybe it's different service schedule in UK? In continental Europe it's 12 months and no recommendations about any additive.

I believe in the UK the recommended service interval is 12 months or 12,500 miles. I would always suggest changing oil at 5000 miles, however they recommend using synthetic oil in the Jazz which should last longer than semi synthetic which I currently use in my cars.

[BadgerMk3]

As others have said, never heard of any modern engine suffering those problems in the UK. Fuel in the US is quite often as low as 87 against our 95 and even their highest rating is only 91-94.

You won't regret buying the Sport, the extra 25% BHP available makes into a lovely little car and I think the subtle Sports body additions make it look much more desirable.


Sent from my iPhone

You have to be careful here as the US uses a different rating system for their fuel.

In the UK (and a lot of Europe) we tend to stick to RON (Research Octane Rating) whilst in the US it's common to see AKI (Anti Knock Index).
It's a bit more complicated than that - I haven't mentioned MON and PON for example - but there's plenty of information available on the internet to explain.

Typically AKI is 4 - 6 points lower than RON, so US AKI 91 fuel is the rough equivalent of our UK 95 RON.

In the UK, most fuels are derived from a base stock which conforms to a British Standard. Some of the 'premium' branded suppliers will then add their own additives at a specific dose rate when filling their tankers at the fuel depot. Again it can get a bit more complicated than that but it's a generic explanation.

Using a good quality fuel and having the services done at the recommended interval using good quality fully synthetic oil conforming to the standard Honda quotes in the handbook should put your mind at rest.

[jazzaro]

I believe in the UK the recommended service interval is 12 months or 12,500 miles. I would always suggest changing oil at 5000 miles, however they recommend using synthetic oil in the Jazz which should last longer than semi synthetic which I currently use in my cars.

In no manual I've read about  synthetic oil recommendations, Honda only specify some ACEA rules or Honda Oils.

[embee]

... It's a bit more complicated than that - I haven't mentioned MON and PON .....
Typically AKI is 4 - 6 points lower than RON, so US AKI 91 fuel is the rough equivalent of our UK 95 RON.
...

Exactly that.

RON is Research Octane Number, MON is Motor Octane Number. The tests are done under different speed/load/temperature conditions. MON is typically 10 numbers lower than RON for a given fuel.
Just for info, the USA normal is to display (RON+MON)/2, so as Badger says typically 5 numbers lower than RON as shown in the UK/Europe.
In addition, fuels in different parts of the world can behave differently even for a given octane number, I had particular experience in industry with issues in New Zealand with fuel characteristics not suiting our cars (or vice versa if you prefer). We couldn't repeat the problem back here with European fuel, we had to send engineers out there to address it "on site".
Sulphur (sulfur .. ) content can vary significantly, which can cause corrosion issues particularly with some plated cylinder bores.
When working at one consultants we had an early BMW DGI engine in for assessment. It had done around 30k km if I recall, and the inlet valves were heavily carboned, I did air flow rig measurements. I don't know what the latest DGI engines are like for this.

[Jazzdriver]

Aren't there two different 1.5 engines?  There was a 1.5 engine available for a short time in what we in the UK call the Mk 3 Jazz.  Then there is the 1.5 Atkinson cycle engine used in the hybrid Jazz and Crosstar.  Aren't they different engines?  Aren't Atkinson cycle engines only used in hybrids, as they are more efficient, but provide less torque, which doesn't matter when they act only to generate electricity for the battery engine or to take over driving the car at higher speeds?

[BadgerMk3]

... It's a bit more complicated than that - I haven't mentioned MON and PON .....
Typically AKI is 4 - 6 points lower than RON, so US AKI 91 fuel is the rough equivalent of our UK 95 RON.
...

Exactly that.


Sulphur (sulfur .. ) content can vary significantly, which can cause corrosion issues particularly with some plated cylinder bores.

I was also going to mention the sulphur content but more in relation to BMW.

My BMW for example, uses a different spec engine oil compared to the US for the same car, because of the difference in fuel constituents affecting the oil.

Back to the Jazz - After all this, I guess simple answer is to use good quality fuel and oil...

[Jocko]

I am sure the Atkinson cycle engines were used in the Mk 3 as well.

[jazzaro]

Aren't there two different 1.5 engines?  There was a 1.5 engine available for a short time in what we in the UK call the Mk 3 Jazz.  Then there is the 1.5 Atkinson cycle engine used in the hybrid Jazz and Crosstar.  Aren't they different engines?

Yep, they are different. The Jazz MK3 had a 1.5 atkinson cycle engine but it was used in the gk5 Hybrid, not imported in Europe and Uk. The 1.5 we had was an Otto cycle.

Aren't Atkinson cycle engines only used in hybrids, as they are more efficient, but provide less torque, which doesn't matter when they act only to generate electricity for the battery engine or to take over driving the car at higher speeds?

Usually Atkinson cycle engines are used in hybrid powertrains because they provide less torque and less power, but there are some atkinson engines used in normal cars, one is the 1.3 16v of the 1.3 MK3 Jazz.

[Jocko]

one is the 1.3 16v of the 1.3 MK3 Jazz.

I knew they were used on some models of the Mk 3 as there have been many comments about the lack of low-down performance.

[Marco1979]

What I heard / read is that the mk4 runs purely in Atkinson mode, while mk3 Earthdreams engines can run in Atkinson mode under light loads and switch to Otto under higher loads. This switching combines performance with economy, but is not needed in mk4 due to the electric motor.

[jazzaro]

What I heard / read is that the mk4 runs purely in Atkinson mode, while mk3 Earthdreams engines can run in Atkinson mode under light loads and switch to Otto under higher loads. This switching combines performance with economy, but is not needed in mk4 due to the electric motor.

1.5 MK4 Jazz is made to run always in Atkinson mode, even if it would be correct to call it Simulated Atkinson mode, since the real Atkinson engine requires a different structure
https://commons.wikimedia.org/wiki/File:Atkinson_Engine_with_Intake.gif#/media/File:Atkinson_Engine_with_Intake.gif
Modern "Atkinson" engines are simple Otto engines performing a Late Intake Valve Closure, so the expansion phase will be longer than the compression. Since the RC in these engines is very high (the 1.3 MK3 Jazz engine runs with a 13,5:1 RC), they would hardly run in cycle Otto mode, this would be dangerous

[Jocko]

@jazzaro. The video isn't there, unfortunately.

[jazzaro]

@jazzaro. The video isn't there, unfortunately.

fixed