[vishy76]

Originally Posted by CretaKumar

I was always passionate about diesel engines, until I bought a Hyundai Creta Bs6. Not sure if I should call it pain in my hass or an absolute devil. Car has Blow by, Oil dilution, and mileage issues. I will explain all below and how all cars (at least Hyundai and Kia) are impacted by this.

All your observations are in line with what most owners have reported internationally too. Let me try and explain all your symptoms:

- Blowby: Some amount of blowby is actually normal in many engines today, especially diesels. Diesel are high compression turbocharged engines and there is bound to be a higher amount of crankcase pressure due to a higher rate of vapourisation of oil.

What you have observed however could actually be harmful to the DPF. Excess vapourisation of oil in the crankcase will eventually be routed into the intake manifold via the PCV and burn off as soot. And I don't think I need to elaborate on what happens thereafter.

Hence, the blowby is something that is normal in context of a diesel without DPF. However, for an engine equipped with DPF, this is definitely harmful. I would also like to know if Hyundai has prescribed a change in oil spec for BS-6 engines. And if yes, what the oil spec is. If no, I would start by changing to an oil compliant with Hyundai BS-6 diesel standards and monitor DPF regen frequency.

- Oil dilution: This is a direct consequence of excessive regeneration. A DPF simply doesn't increase engine speed to regenerate. It also increases fuel injection quantity drastically. There is always a chance that unburnt diesel will stay in the combustion chamber and wash down past the piston rings into your engine oil during the compression stroke.

This is an extremely harmful process as you already might be aware. Diesel has detergent properties. It will end up washing oil off from critical engine components like bearings and piston rings and accelerate component wear. An increase in engine oil level due to fuel dilution is something that simply cannot be ignored.

Your last point about frequent regens explains the first two symptoms very well. The DPF is getting clogged chiefly due to short trips and driving conditions and also due to the oil (though it's difficult to determine how much of a role the oil is playing in this entire episode).

Frequent regens are causing oil dilution which in turn is increasing your engine oil levels too. It is also obviously hurting fuel efficiency drastically.

I would start by analysing what I can control from the above. I think you should start by researching what oil Hyundai India is using for these engines. If they are using the same oil as BS-4 engines, you have your culprit. Simply change the oil and see if the DPF regen frequency decreases. Driving style is something that is difficult to change, especially in city limits.

BS-6 diesels are a pain in the proverbial place. Sometimes I do think it's better that diesels make a graceful exit from the automotive scene, rather than making owners suffer due to complex and sensitive emissions control equipment. Not to mention, DPFs are expensive to replace when they do go bad, which they will eventually after a certain number of regen cycles.

[crdi]

So, the general understanding is that low speed/low rpm driving would cause these hiccups. If that is the case, how is this system programmed in trucks?
Agreed that they do long distances non-stop but, isn't heavy hauling usually low rpm?

[audioholic]

Originally Posted by crdi

So, the general understanding is that low speed/low rpm driving would cause these hiccups. If that is the case, how is this system programmed in trucks?
Agreed that they do long distances non-stop but, isn't heavy hauling usually low rpm?

The whole thought of higher RPM running is to minimize lugging and at the same time have higher EGTs to burn off the soot in the DPF. Smaller engines burn lesser fuel and hence the EGTs are also on the lesser side under less load and less engine speed. But for larger diesel engines, they run at lower speeds if you compare with a smaller engine, but thats where they can also operate with lesser soot production as well as manage to keep EGTs on the higher side due to their higher capacity and their load. A Volvo bus engine is designed to run efficiently at even 1K RPM, which is not necessarily the case with a 1.5L Diesel engine in a small car. So the exhaust after treatment components are also designed to suit this. Same would apply for gensets and other diesel engines which are usually running at lower RPMs.

[car-dent]

We have recently bought a Diesel i20 and have a BS6 Innova since last 2 years. Haven't faced any issue so far in either of them . The i20 has been driven 4000 odd kms so far and innova about 20,000kms. Neither car has gone into regen even once.

[sbm]

While BS6 diesels have DPF issues, Hyundai TGDi engines have turbo failures, and the Skoda 1.0 Tsi has EPC and AC issues. The only reliable engines today are the Honda 1.5 NA and Maruti and Hyundai's petrol lineup. What's common with these problematic powertrains is that they've been introduced in the last 5 years in India.

[srikanthmadhava]

Originally Posted by vishy76

I would also like to know if Hyundai has prescribed a change in oil spec for BS-6 engines. And if yes, what the oil spec is. If no, I would start by changing to an oil compliant with Hyundai BS-6 diesel standards and monitor DPF regen frequency.

Yes, Hyundai has changed the oil spec for its BS6 Diesel cars.
For Creta, they recommend 0W20 ACEA C5 spec oil for BS6 diesels, compared to BS4 spec ACEA A3/B4 - SAE 5 W 30.

So, their BS6 diesel oil recommendation is upgraded for use with DPF.


Refer Hyundai Oil Recommendation

Refer ACEA-C5-16

ACEA C5 oils are a new addition to the ACEA 2016 Oil Sequences. ACEA C5 oils are Top Tier lower SAPS1 lubricants. They are designed for use in high performance gasoline and light duty diesel engines where advanced aftertreatment systems such as Diesel Particulate Filters (DPFs) and Three Way Catalysts (TWC) are used.

Originally Posted by vishy76

If they are using the same oil as BS-4 engines, you have your culprit.

Now, this is an open question.
Are the authorised service centers using the recommended BS6 spec oil or are they simply continuing with their old BS4 oils?
I have had experience with HASS using BS4 oil in my BS6 Creta. I validated the spec and my doubts came true. They accepted the mistake and changed the oil right away, by opening a New barrel of Shell ACEA C5 oil.

Not sure how many unsuspecting BS6 diesel car owners would have already gone ahead with the BS4 oil itself, after all, its added by their trusted service center.

This was at the start of BS6 phase, I am not sure about current situation though. And this is not applicable to KIA, since they never had a BS4 car.

I have a BS6 Creta Diesel Automatic, completing 2 years and 22K Kms. I have not faced any issue with DPF as of now (I mean, no DPF warnings as of now . No idea on blowby, dilution or mileage issues), but majority of usage has been on highways.
I get great mileage on highways (15 to 21kmpl depending on the road conditions, ghats etc).
I get terrible mileage in cities (9 to 12kmpl depending on traffic), especially in short city trips.

[CretaKumar]

Originally Posted by vishy76

All your observations are in line with what most owners have reported internationally too. Let me try and explain all your symptoms

No BS6 engines have a different spec lubricant. This was my first question when I was brainstorming about it. but got the answer on first service that Bs6 creta uses 0w20 acea c5 engine oil which is dpf compliant.

[naikameya]

I see this ad. Has anyone researched it?

[Brumby]

Originally Posted by CretaKumar

This is my first post here. So I will be very particular about words and scenario I use here.

Originally Posted by vishy76

All your observations are in line with what most owners have reported internationally too. Let me try and explain all your symptoms:

Blow-by is leakage of gases from the cylinder to the crankcase and is an indication of the condition of the piston rings. Usually an engine cylinder having weak piston rings or leaky piston rings will have blow-by. This usually happens during the last stages of the compression stroke or during the combustion process when the pressure reaches its peak inside the cylinder. Usually blow-by will happen at higher loads and if it happens at engine idling that means you need to overhaul the complete cylinder liner, pistons and piston rings.

A blow-by is associated with black/blue smoke from the exhaust and will result in loss of lube oil as the oil layer for cylinder lubrication will burn at the surface of the liner where the blow-by is taking place. A continuous blow-by will result in micro-seizure and eventually complete seizure or crankcase explosion.

The oil vapour escaping the dip stick tube or from the crankcase vent is the vapour of the oil formed due to hot oil splashing in the crankcase while the engine is running. This vapour will be less on a cold engine and will be slightly higher on an engine which has run for a long time and is operating at its optimum engine block temperature. It is normal for such vapour formation until a pressure can be felt when we put our thumb on the vent/tube for dipstick.

The present day engines run on higher liner temperatures due to higher peak pressures and better metallurgical properties achieved. Earlier generation engines used to run at about 80-85 degrees C liner temperatures, wheres as present day engines run at about 95 degrees C. My MY2014 Polo TSI runs at 90 deg C. This results in higher average engine block temperature. The lube oil temperature at engine inlet is about 65-75 deg C and outlet from engine (draining from the crankpin & main bearings and piston) is usually 10 deg C higher than the engine inlet temperature. The lube oil coming out at about 80 deg C will definitely have some amount of vapourisation which will escape through the openings connected to the crankcase (dip-stick tube, vent etc)

Oil dilution is caused due to mixing of fuel (diesel/petrol) in the lube oil and will result in low lube oil pressure which will over a period cause wiped out bearings and seizure of the engine.

Mixing of coolant in the lube oil will cause emulsification and will lead to choking up of the oil filters and in a severe case oil will become like gel/paste.

In your case there is no blow-by nor dilution of the oil. Oil level varies in the engine depending on the oil temperature and if the engine is running or is stopped.

Oil level on a cold and stopped engine might show increase after running the engine and checking about 15-20 minutes after stopping. The oil volume will increase due to increase in temperature.

Oil level will show reduction if you compare the levels before starting and immediately after running a cold engine. The oil volume has been pushed into the system and is still cold hence reduction in the level in crankcase.

The correct way to check oil level is to bring the engine to its normal operating temperature, take the dip stick out, wipe with a clean rag and dip it again. Take it out immediately and what shows on the dip stick is the actual level of oil in the engine.

Most of the people working at the service centers have either no theoretical knowledge or its forgotten. Usually the people servicing our cars only know how to dismantle and assemble components of a car, very few people also know the theory related to the design of the parts and the equipment and I have hardly come across anyone (Suzuki, Toyota & VW).

A lot of research goes into designing the mass market equipment, due to higher tolerance levels there are incidents of failures as well as compared to high value equipment where the tolerance levels are very narrow.

Dealing with the particulate matter and sulphur content of the exhaust gases is a newer concept and will take a little time to get fine tuned and settle down. Please remember the first diesel engine almost exploded and the present day diesel engines are running at very high peak pressures (Almost 180-200 bar).

The engines are good, its the DPF which the manufacturers need to improve on.

Cheers

[varunsangal]

Originally Posted by CretaKumar

My final take is to avoid buying Hyundai diesel engines. I am not speaking for myself, I am speaking on behalf of 118 users from my whatsapp group who are facing same issue. Creta is no doubt a practical car but it seems like there is a lot of things not good about Hyundai diesel engines in 2021-2022.

It's a rather long shot, but worth checking...

During your last service was the oil filter changed?

If not, the residual oil in the filter (can be ~>100 ml) + the new oil filled in may have caused to overall oil level to have gone above the recommended limit. Once this happens, all the conditions you describe is bound to happen. Burning oil will cause soot build up, cause DPF to get clogged up and cause low average and blow-by.

The solution:

1. Empty the oil sump.
2. Clean out the oil filter/stick in a new one.
3. Fill in oil to exact factory specified amount.
4. Clean out injectors.
5. Clean out the intercooler.
6. Clean out DPF

Once done drive the car as normal, should ideally be solved.

Also, as suggested by the other, an Italian tune-up once in a while is good for the car.

[CretaKumar]

Oil filter was changed

[callmeneo]

Shouldn't Kia Diesel owners face the same issues considering the powertrain is same?

[Phantom 510]

Dpf equipped diesel cars if driven well wouldn't throw up tantrums like most of the people accuse them of. We have a Nexon diesel BS6 MY2021 in our family. It is used for highways as well as commutes (however, very short commutes are avoided) and yet to throw any dpf regen signals. Thanks to the pre purchase dpf research i got to know that enough heat and gas flow needs to be generated to burn off the soot. So whenever situations permit or out on the open roads it is made sure to be driven consciously at 3rd/2000rpm for 15-20 minutes to generate enough heat and required exhaust gas flow to burn off the soot even if it's not showing dpf regen signals. It has worked wonderfully well and doesn't seem to be a hassle. Certain things has to be kept in mind before setting out for a drive but that's okay when positives are plenty. The fuel efficiency, torque and longevity is still unmatched. I am glad that dpf has brought toxic emission levels down by a significant margin and as a result diesel cars have become a lot cleaner. I must mention about the Honda's 1.5L i-Dtec, which is a rare gem amongst the dpf equipped diesel cars. It's regeneration happens at speeds just above 20 kmph which is a blessing as others needs to be at around 60-65kmph in 3rd gear or 2000rpm.

[CretaKumar]

Originally Posted by Phantom 510

Dpf equipped diesel cars if driven well wouldn't throw up tantrums like most of the people accuse them of.

Same thing that service center people say. Are you Hyundai service center guy who drives a tata?

[sbm]

I would like to share my experience with DPF. I took my XUV700 diesel manual for its first service at 1000km. 600 km were in the city and 400 km were on the highway. The city drives don't have any stop-go traffic as ours is an industrial town with mostly free-flowing traffic. The highway drives were out of town, 1-2 hr trips to nearby tourist attractions at speeds ranging from 70-90 kmph. When the mechanic connected his laptop to the car, it showed a 19 gramme soot deposit. Although there was no dpf warning on the car's instrument panel, he initiated service regeneration from his laptop. I saw that the condition for service regen is 0 to 37 grammes of soot deposit and a certain exhaust gas temperature and coolant temperature. I asked him when I would have gotten the warning had I not come for service, to which he had no answer. He said that the car must have been removing deposited soot periodically, hence the warning. Due to him doing service regen (not a bad thing though, good move on his part) , I now don't know whether my drive pattern is good for passive regen or not.

Now, I observed the service regen process and, combing the observations from bhpian @ravenavi's post on his XUV thread, I learnt a crucial thing, but this is applicable only for cars equipped with the park regen feature. The service regen or park regen process consists of two heating stages and one regen stage. The total time for them is approximately 20 minutes. If anyone gets a 1st stage DPF warning, instead of starting the regen process in a cold engine, try to do a small trip of 4-5 kms not involving more than 1 stop in between, and as soon as you return home, initiate the regen process. This way, the heating stage will be skipped or minimised, and instead of wasting fuel for heating, it'll be used for some travel. In short, try to initiate park regen or service regen on a hot engine rather than a cold one. This is my opinion/theory and is not based on any official recommendation. Please point out if you guys see any harm in following this method.