going thicker with variable displacement oil pump

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May 31, 2016
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Vienna, Austria
I have a 1.6 litre FCA Diesel engine with a variable displacement oil pump, the car is equipped with a DPF and urea NOX system. Factory calls for 0W20 (Acea C2! Try to find an 0W20 C2 oil other than the manufacturers oil!) oil, the same engine the year before (apparently also with a variable displacement oil pump) called for 0W30 (Acea C3) oil. The years before 5W30 (Acea C3) and the base engine block used since mid 00's used to use 5W40 (A3 w/o DPF).

I do encounter oil dilution (as I had with all my DPF cars before, regardless of the manufacturer) - I'm a tad bit worried that the 0W20 becomes a 0W16 or below. Maybe thats why the car only has a 1 year official service interval where it used to be 2 years with x30 oils.

Right now I'm running 5W30 (Acea C3) - with no apparent noticeable ill effects. Since I'm only using that particular car from spring through summer til early fall - I already had in mind going to a C3 5W40 or even a HDEO 10W30.

But I'm concerned with the variable displacement oil pump, which might keep the oil pressure at a low level during cruise. We all know that oil pressure euqals resistance to flow, so having a thicker oil with a variable oil pump with low pressure might end up with too little oil flow?


What I've gathered so far:
a.) I have no idea how the variable pump is designed, or how the software is designed to operate. All I know is that I have a variable pump and that the car is from an era where every last microgram of CO2 reduction is tried to achieve.

b.) While the car is intended to run on 0W20 (Acea C2) oil - even that gets thick in very low temperatures. So in theory a 10W30 in hot summer might be at the same cold start viscosity as a 0W20 in very very cold weather. Since the lather has to work someone might assume the first has to work too. What I dont now here is wether the ECU and its oil pressure regulation system does take outside temperature into account.

c.) How much thicker can I go in terms of operating viscosity without throwing everything out of balance? A respected member on here once wrote that a normal working engine without problems cant be destroyed by any regular viscosity oil. But is that also true with variable displacement pumps that keep pressure to a minimum?

d.) The car might throw codes when too thick of an engine oil is used, but so far I haven't seen any indications with 5W30 C3 instead of the 0W20 C2 oil yet under any circumstances.

e.) The car does see high oil temperatures, at 248°F I slowed down drastically since I got worried with the 0W20 factory fill thinning out too much. One might say the engine has been designed around 0W20, but I personally am not so sure. Basically this engine before used to run on 5W40 - 5W30 - 0W30 before, (older engines pre '10 - 10-14, 14 - 18). 2019 up, where only urea NOX was added suddenly changed to 0W20. My personal opinion is that 0W20 with Acea C2 is used to try to get the consumption as low as possible, but the manufacturer is maybe worried, so its a ACEA C2 0W20 (which is also only availabe from the manufacturer).
What if I have to tow in hot summer with the 0W20 and already high temperatures (which I guess is intended, as a lot of newer cars tend to run a hotter temperature level)? That 0W20 might thin out to a 0W10 due to excess heat?

f.) 6000 miles on 5W30 and the car runs great, oil analysis shows reduced wear. But I know from previous generations (that had no variable oil pump, and earlier versions of the variable pump that might had different software targets) that the engine itself loves 5W40, 10W40 oils. Much better wear metal results. So I would like to make my way back to a 40 weight oil - but I'm unsure wether I might do long term damage due to too much reduced oil flow (a 40 vs a 20 at operating temp at the same pressure the 40 flows much less than the 20) - without noticing it before its too late.


So right now I'm on the fence ... 5W30 Acea C3, 5W40 Acea C3, 10W30 CJ4, 15W40 CJ4 DPF compatoble oils are all available in my personal storage shed.


Whats your take on this?
 
Joined
Feb 6, 2021
Messages
774
Yeah a 0w20 or 0w16 in an engine that was not initially intended to run on it due to emission regulation, there are 10w30 and 15w40 oils with very low zinc and phosphor,

delo 600 is good for that.
 

alex_at

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Delo 600 is not available in Europe as far as I've seen, but I do have some DPF compatible 10W30 and 15W40 on hand.
 
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If its like most systems, its only a high/low pressure. Oil temp/pressure/engineload/RPMs etc are used and the software decides if it wants high or low pressure. So even if oil is a little" too thick" its not going to drop below what ever has been determined software wise to be too low. May it switch to "low" a little sooner? Maybe, be would a very small percentage sooner I would think. I have only seen them switch to low on gas FCA stuff during very cold start, or low load/rpms. I certainly wouldnt run 0/20 if it was mine, esp. if run hard/and/or with high oil temps. They tried creeping down to a 5/30 on the early ecodiesel and it bit them in the a$$. ALL the FCA diesels, don't have what I would consider a robust design at all, and I would atleast bump up to a 0/30. This in an Alfa? We dont get the small diesels over here, so I can only pull up limited info.
 

alex_at

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yes it is in an Alfa. The 1.6 multijet is based on the legendary 1.9 JTD engine which many consider one of the best common rail diesel engines. I had 2 of the old 1.9 JTDs (which used 5W40 oil btw), a 2.4 5cyl JTD and now the 1.6 Multijet 2 which basically is a smaller bore version of the old 1.9.

Never had any troubles with these FCA diesels. Easily as reliable as the old Mercedes diesels. Had more trouble with my 3.0 V6 TDI Audi than I ever had with any FCA engines....



The thing with the 1.6 multijet 2 is - I don't know anything about the system programming in regards to the variable oil pump. Unfortunately no really detailed info out there, and the dealer mechanics won't give out any detailed info.(If they even know themselves...) I tried AlfaOBD and MultiECUScan- but can't read the oil pressure (at least not yet). Thats the one thing I really miss about my VW/Audi ownership -> VCDS.

on the gas FCA's: what is considered low load? Where's the cutoff to switch from high to low oil pressure?

The EcoDiesel - I've read about these - as far as I remeber aren't those VM Motori engines - so technically not an FCA?
 
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yes it is in an Alfa. The 1.6 multijet is based on the legendary 1.9 JTD engine which many consider one of the best common rail diesel engines. I had 2 of the old 1.9 JTDs (which used 5W40 oil btw), a 2.4 5cyl JTD and now the 1.6 Multijet 2 which basically is a smaller bore version of the old 1.9.

Never had any troubles with these FCA diesels. Easily as reliable as the old Mercedes diesels. Had more trouble with my 3.0 V6 TDI Audi than I ever had with any FCA engines....
Good to hear the smaller ones are better. The bigger ones over here certainly are not!😁 The 3.0L 4 and 6cyls(2014-19) are absolute junk. So far knock on wood, the newer gen v6 has been good.
 
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I take it then this is a FCA design not VM? Pics i can see, it looks to have a similar block design to the FCA gas 1.4 we use over here.
 

alex_at

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which one?

The EcoDiesel is a FCA / VM - who designed what is beyone me - but VM motori is owned by FCA since a few years, so I guess both share technologies...

My 1.6 multijet is a true Fiat Powertrain engine
 

4WD

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which one?

The EcoDiesel is a FCA / VM - who designed what is beyone me - but VM motori is owned by FCA since a few years, so I guess both share technologies...

My 1.6 multijet is a true Fiat Powertrain engine
What is the range of pressure you see in both high and low stages ?
 
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What is the range of pressure you see in both high and low stages ?
I honestly dont remember.....I will watch on the next one I log and take a pic. I think around 20-25 psi?? We see sol. failures on the 3.6 , so they stay on high, and flag a code. So we log oil pressure and on/off state of sol, and watch to see if we see a change. Failure can be either electrical( open sol.(in engine), or external wiring, or sometimes wrong filter/damage inside filter housing etc. They will flag same code sometimes, as sol. circuit is not monitored for continuity. Oil pressure is watched and software just determines its out of spec. Saw this alot when they switched filter styles and qwick lubes would jam old version filters in new style housings. ....creates an internal oil "leak".
 

4WD

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i dont see any pressures yet in my diag software (AlfaOBD, MultiECUScan) ...
I have owned several US vehicles with these pumps … they are ECM “demand based” and can deliver plenty volume/pressure in the high stage as required … (parameter monitoring) …
If it’s a vane style pump - it’s very efficient (high 90’s) with standard PVL viscosity …
 

4WD

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I honestly dont remember.....I will watch on the next one I log and take a pic. I think around 20-25 psi?? We see sol. failures on the 3.6 , so they stay on high, and flag a code. So we log oil pressure and on/off state of sol, and watch to see if we see a change. Failure can be either electrical( open sol.(in engine), or external wiring, or sometimes wrong filter/damage inside filter housing etc. They will flag same code sometimes, as sol. circuit is not monitored for continuity. Oil pressure is watched and software just determines its out of spec. Saw this alot when they switched filter styles and qwick lubes would jam old version filters in new style housings. ....creates an internal oil "leak".
Sorry - what 3.6L ? Pentastar ?
 
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yes it is in an Alfa. The 1.6 multijet is based on the legendary 1.9 JTD engine which many consider one of the best common rail diesel engines. I had 2 of the old 1.9 JTDs (which used 5W40 oil btw), a 2.4 5cyl JTD and now the 1.6 Multijet 2 which basically is a smaller bore version of the old 1.9.

Never had any troubles with these FCA diesels. Easily as reliable as the old Mercedes diesels. Had more trouble with my 3.0 V6 TDI Audi than I ever had with any FCA engines....
Can confirm, had the 1.9 TD (before the JTD / common rail injection system was ready) that was very reliable.
I doubt the current 1.6 has much in common with my old 1.9 that was designed in the mid 90's, but like most of the Fiat "modular" engines from that era, I can see common roots.
 
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down in the park
I have a 1.6 litre FCA Diesel engine with a variable displacement oil pump, the car is equipped with a DPF and urea NOX system. Factory calls for 0W20 (Acea C2! Try to find an 0W20 C2 oil other than the manufacturers oil!) oil, the same engine the year before (apparently also with a variable displacement oil pump) called for 0W30 (Acea C3) oil. The years before 5W30 (Acea C3) and the base engine block used since mid 00's used to use 5W40 (A3 w/o DPF).

I do encounter oil dilution (as I had with all my DPF cars before, regardless of the manufacturer) - I'm a tad bit worried that the 0W20 becomes a 0W16 or below. Maybe thats why the car only has a 1 year official service interval where it used to be 2 years with x30 oils.

Right now I'm running 5W30 (Acea C3) - with no apparent noticeable ill effects. Since I'm only using that particular car from spring through summer til early fall - I already had in mind going to a C3 5W40 or even a HDEO 10W30.

But I'm concerned with the variable displacement oil pump, which might keep the oil pressure at a low level during cruise. We all know that oil pressure euqals resistance to flow, so having a thicker oil with a variable oil pump with low pressure might end up with too little oil flow?


What I've gathered so far:
a.) I have no idea how the variable pump is designed, or how the software is designed to operate. All I know is that I have a variable pump and that the car is from an era where every last microgram of CO2 reduction is tried to achieve.

b.) While the car is intended to run on 0W20 (Acea C2) oil - even that gets thick in very low temperatures. So in theory a 10W30 in hot summer might be at the same cold start viscosity as a 0W20 in very very cold weather. Since the lather has to work someone might assume the first has to work too. What I dont now here is wether the ECU and its oil pressure regulation system does take outside temperature into account.

c.) How much thicker can I go in terms of operating viscosity without throwing everything out of balance? A respected member on here once wrote that a normal working engine without problems cant be destroyed by any regular viscosity oil. But is that also true with variable displacement pumps that keep pressure to a minimum?

d.) The car might throw codes when too thick of an engine oil is used, but so far I haven't seen any indications with 5W30 C3 instead of the 0W20 C2 oil yet under any circumstances.

e.) The car does see high oil temperatures, at 248°F I slowed down drastically since I got worried with the 0W20 factory fill thinning out too much. One might say the engine has been designed around 0W20, but I personally am not so sure. Basically this engine before used to run on 5W40 - 5W30 - 0W30 before, (older engines pre '10 - 10-14, 14 - 18). 2019 up, where only urea NOX was added suddenly changed to 0W20. My personal opinion is that 0W20 with Acea C2 is used to try to get the consumption as low as possible, but the manufacturer is maybe worried, so its a ACEA C2 0W20 (which is also only availabe from the manufacturer).
What if I have to tow in hot summer with the 0W20 and already high temperatures (which I guess is intended, as a lot of newer cars tend to run a hotter temperature level)? That 0W20 might thin out to a 0W10 due to excess heat?

f.) 6000 miles on 5W30 and the car runs great, oil analysis shows reduced wear. But I know from previous generations (that had no variable oil pump, and earlier versions of the variable pump that might had different software targets) that the engine itself loves 5W40, 10W40 oils. Much better wear metal results. So I would like to make my way back to a 40 weight oil - but I'm unsure wether I might do long term damage due to too much reduced oil flow (a 40 vs a 20 at operating temp at the same pressure the 40 flows much less than the 20) - without noticing it before its too late.


So right now I'm on the fence ... 5W30 Acea C3, 5W40 Acea C3, 10W30 CJ4, 15W40 CJ4 DPF compatoble oils are all available in my personal storage shed.


Whats your take on this?

It's not an issue. The pressure only rises because flow demands are met.

The oil pump has a target oil pressure checked by an oil pressure switch, you get a code if that pressure isn't met.

As you know I've been running 0w30 A3/B4 in mine, also with variable flow oil pump. I'm at 161.200 km now, did 30.000 km in total on C2 oil
 
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Alex, I understand your concerns, but I'm convinced it's a non-issue. I'd keep running C3 5W-30.
I like these Fiat/Alfa Multijet Diesels and I would just choose an oil meeting VW 507 00/MB 229.51/BMW LL-04 preferably. Shell Helix Ultra Professional AV-L 0W-30, M1 ESP 5W-30 and Ravenol VMP 5W-30 and REP 5W-30 would be my take. Shouldn't be hard to obtain at all in Austria.
 
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