Oil selection for LPG-powered Fiat Stilo 1.6, oil consumption deep in the OCI

[Zyborg]

Hi everyone. I've been a huge fan of BITOG, I've read more than 1000+ threads in the past 2 years. This is my first post and I need your insight.

I own a 2002 Fiat Stilo with the 1.6 16v DOHC 4 cyl "Lampredi" engine (182b6000) with 195k miles on the clock. I bought it used for fairly cheap last year. The engine feels strong, goes 130 mph on a straight line without much effort. Manual calls for 5W30 (for -20C) and 10W40, API SJ, ACEA A3. Updated manual calls for 5W40 FIAT 9.55535-M2 and OCI of 30k kilometers (18.75k miles) or 1 year.

So far, I've done 2 oil changes: the first one using mid-SAPS Fuchs TITAN GT1 SAE 5W-40 (API SN, ACEA C3). Ran it for roughly 4.2k miles. What's interesting is that I had practically zero oil consumption during the first 1800 miles, however, in the next 2400 miles the engine used 1.1 quarts of oil (roughly half quart/1000 miles). I then opted to change it for a semi-syn full-SAPS Elf Evolution 700 STI 10W-40 (API SN, ACEA A3/B4). Same behavior but this time the oil consumption started much faster, at just 1250 miles. Since then I've done another 1100 miles and the oil dipstick is just below the half mark. I have to mention that no smoke is coming out of the exhaust when up to temperature (except very early in the mornings, the usual moisture smoke as I drive short distances). My mechanic had told me that one of the gasoline injectors was somewhat "faulty" (leaky?) and in some cases it caused misfires for 10-15 after a hot start on one cylinder. Pressing the gas pedal 2-3 times for up to 4k rpm resolved the misfires instantly.

So coming to today: I decided to install a EuropeGas LPG system in this car. Reason? I like this car and I don't plan to sell it anytime soon. The price difference in Greece is more than 50% compared to gasoline so I will break even in less than 6k miles. The car runs very smooth and feels like it has more power on LPG. I also have to mention that this exact same engine has been used on the Fiat Doblo 1.6 Natural Power and it runs on CNG (methane) with the only difference being ECU and intake manifold. So obviously the engine is pretty well built to sustain the extra stress (if any) of the LPG.

What could be the reason for the oil consumption deep in the OCI? Could it be fuel dilution or just oil oxidation due to heat? What oil do you recommend me to use in the next OCI (and first under LPG operation)? Should I go mid-SAPS again or stick to full-SAPS? I plan to change my oil every 5000 miles. Some BITOG people said that I could use a CNG/LPG specific oil but these are hard to come by and are pretty expensive. Many point that LPG burning while doesn't make oil dirty (as it is cleaner than gasoline) it combusts at a higher temperature and can lead to oil nitration (HNO3).

 

[Bailes1992]

First thing, a litre of fuel every 2500miles is far from serious. But understand it's not ideal.

Assuming the oil is being burned and isn't leaking then I'd look to replace the PCV as that's likely tired.

The other thing is the possibility of carbon in the ring lands of the piston. I know a lot of people have has success with piston soaks, so have a search around here for that. Personally I'd look to use Mobil1 FS 0w40 as it does contain esters which can clean over time.

 

[Zyborg]

Well, as far as I know, my engine doesn't have a PCV valve. Just a breather (ventilation?) hose. Maybe I should check if it's clogged or something. Your idea about esters is pretty much what I thought. A good quality base oil that won't oxidate easily. The reason why I haven't used esters so far has to do with concerns about my valve stem seals.

About the oil choice: Mobil1 FS 0w40 is well respected here in Europe but it's kind of difficult to get the German-made one. The Polish version is of lower quality (as Piotr's tests have found). My oil shortlist for the next change is:

1. Mobil1 FS 0w40 (German version). 13.50€ per liter
2. PETRONAS SYNTIUM 3000 AV 5w40. 8.16€ per liter
3. Mannol Extreme 7915 5w40. 5.98€ per liter
4. Aral HighTronic 5w40. 6.00€ per liter
4. Liqui Moly Molygen 5w50 (old formula, API SL). 11.34€ per liter
5. Castrol Edge Titanium FST 5w30 LL. 10.50€ per liter

From the above oils, ester content have (with 100% certainty) the Mobil1 and the Mannol. All of these are full synthetic, meaning Group III+. For the last 2 oils, I could follow the "one grade thicker" consensus in the summer and see if the oil consumption drops. This LM 5w50 is not overly thick (HTHS < 4.00 if I recall correctly) and has good NOACK (7.5%). Maybe next winter I could also go one grade thinner? At least the manual states that it can work, although for sure the engine has some wear after almost 200k miles.

One more thing: do you think that I need a lot of ZDDP, i.e., sticking with a A3/B4 full-SAPS oil? My engine has hydraulic valve lifters with rocker arms, so no flat tappers to wear there. I'm also thinking about the life of my catalytic converter.

I don't want to reduce the oil consumption to zero. The LPG mechanic told me that some oil consumption (150ml/1000km) is probably good for the life of the valve seats, as the ash the oil leaves when it's getting burned makes the metal-to-metal contact less severe. But I also don't want to pick an expensive oil and then see the consumption to increase. I will probably do a UOA of this Elf 10w40 oil in my next oil change.

 

[DV0993]

Γεια σου Zyborg!

Good theory from your mechanic on the valve seats - It would be interesting to know if the CNG version of your vehicle came with hardened valves or if they used the one in the petrol version.

I too have experienced oil consumption later in an OCI and put it down to the oil deteriorating (I could be wrong, though)

For eg. I had an old wrx that burned about 300ml after 4000km (oci was every 5k).

I'd run a good 10w40 (maybe even a 15w40 in summer) - One of my vehicles is an LPG converted ford falcon (australia) - for whatever reason, they recommend 15w40 for LPG vehicles here.

If you can get Penrite oil in Greece give it a try. It has a good dose of zinc and is compatible with Lpg vehicles

 

[oggb]

Updated manual calls for 5W40 FIAT 9.55535-M2 and OCI of 30k kilometers (18.75k miles) or 1 year.

Yeah... don't do that. 5 to ~10k miles/8 to ~16k km would be much more reasonable, though some vehicles, when run on LPG, can extend their oil change intervals. Not sure I would on a known oil-burner.

What could be the reason for the oil consumption deep in the OCI? Could it be fuel dilution

Some quick google searches seem to indicate that your engine is known to burn oil. The fuel dilution from a leaky injector certainly wouldn't help.

Like @Bailes1992 said, it could also just be a case of clogged oil control rings, especially if the previous owner was actually going 30k km between oil changes.

One more thing: do you think that I need a lot of ZDDP.

No. Even newer flat tappet engines don't even need thick oil or extra ZDDP. My Prius and Subaru both have flat tappets and I run regular 5w30 in both.

 

[Zyborg]

Hi DV! Greetings to patrida in Melbourne!

The CNG version had the exact same engine code (182b6000) and searching for the part numbers for valve guides and inlet/exhaust valves, the FIAT OEM codes are exactly the same. I cannot check the valve seats because I cannot find it as a standalone part; it's officially only sold with a whole cylinder head. LPG or not, there will be valve seat wear anyway but I want to minimize it (but without using ridiculous amounts of oil).

The idea of 15w40 is a solid one but the best 15w40 I can find are HDEO which is something that might not be good if the oil consumption doesn't go down. Shell Rimula R4L 15w40 comes to mind as a good "pure" group II dino oil (15.5 cst @100 C temp) but is has no API certification for use in gasoline engines.

Specs based on the 2012 Rimula R4L I found on pelicanparts DOT com website:
Rimula R4 L
Zn content 1230 – 1430 ppm
P content 1110 – 1280 ppm
Magnesium ???
Calcium ???

Based on this, the only difference is Phosphorus compared to my Elf 10w40 (Zn 1306 ppm, P 985 ppm). I've read in BITOG that Phosphorus up to 1300 ppm is OK for gasoline engines. Maybe I should give it a try in 3 months time (May here is already 30+ C degrees). Penrite is pretty much nonexistent here unfortunately...

 

[Zyborg]

Like @Bailes1992 said, it could also just be a case of clogged oil control rings, especially if the previous owner was actually going 30k km between oil changes.

As he gave me the original service manual (since the car was new) he indeed kept the oil for 20k km between the oil changes. He was using Selenia 20K 10w40 which was the recommended oil back when Selenia was owned by Fiat. But most of the mileage was outside of the city traffic, because the car actually did 96k km in the first 4 years. The car was in Volos, so it makes sense that he did multiple Volos-Athens trips in that period. He never left the oil longer than a year though.

But the oil consumption deeper into the OCI tells me that something in the engine causes the oil to degrade faster, probably due to thinner passages due to clogged oil control rings? In this case a thinner oil could actually reduce oil consumption because it will flow quicker.

 

[kschachn]

But the oil consumption deeper into the OCI tells me that something in the engine causes the oil to degrade faster, probably due to thinner passages due to clogged oil control rings? In this case a thinner oil could actually reduce oil consumption because it will flow quicker.

Clogged oil passages has zero to do with the grade here. It has to do with the ability to resist ring sticking and deposit formation. That’s not connected to grade.

 

[userfriendly]

I've owned 7 LPG trucks, all 454s or 350 SBCs. All of them out lasted the vehicles running 15w40 summer and 5w40 HDEOs winter, with
the exception of a 350 1500 chev van running 15w50 Delvac year round with 30,000 mile drain intervals.

Railroad GMC and Chev SBC 3500 vans used for deadheading rail crews were traded at one million miles, or about 6 years, running either
10w30 or SAE30.

All the RR LPG engines used about one litre per 2,000 miles. Mine with forged pistons and additional ring clearance, about the same with
the thicker xW40 oil.

If your engine has aluminum heads, it has the hard valve seats. My iron heads had hard seats and stainless valves installed.

Because of the oil consumption, I would not recommend using a high ash engine oil on vehicles with emission controls intact.

 

[Zyborg]

I've owned 7 LPG trucks, all 454s or 350 SBCs. All of them out lasted the vehicles running 15w40 summer and 5w40 HDEOs winter, with
the exception of a 350 1500 chev van running 15w50 Delvac year round with 30,000 mile drain intervals.

Wow, LPG on carbureted 7.4L V8! And here some people are afraid to put LPG on BMW straight-6s. Did you notice if the oil turned black after such long OCIs?

If your engine has aluminum heads, it has the hard valve seats. My iron heads had hard seats and stainless valves installed.

Because of the oil consumption, I would not recommend using a high ash engine oil on vehicles with emission controls intact.

Yes, it has aluminum heads and cast-iron block so yes, it should indeed have hard valve seats. Don't really know the material of the OEM valves but being the exact same as on the CNG model, they should also be fine.

So the choice will be between full synth 5w40 or dino HDEO 15w40 or 10w40.

 

[userfriendly]

I used miles instead of kms for our American friends. 30k miles = 50k kms. Change the oil when it's on the add line, save a buck or two.
With the oil consumption the way LPG engines are, the oil is self changing, and because LPG is clean burning, the oil stayed clean forever, it seemed.
The pistons run hotter with LPG, and the top rings call for additional clearance on engine rebuilds.

Not every LPG engine uses oil. I did a 10.5 cr 454 that went into a 87 Suburban and the owner said that the engine never burnt a drop of oil.
I used 0w40 Delvac in my mother's 454 10.5 LPG engine, only because she lived on the Canadian prairies, (about 200 miles north of Minot, ND) and needed -40C/F cold start protection.
I used 15w50 in my son's GMC van with a 10:1 350 SBC, because it never left the west coast during winter (Whistler), he was bad for checking
oil and the heads had better springs and a little more cam.

Unless you need 5w or 10w winter grades for cold start performance, LPG engines will go 1.6 million kms on just about any engine oil, so
"synthetic" is a waste of $$ imo.

edit; The 454 in the 87 suburban took out the 4 speed , 700R4, od transmission in short order.

 

[sk_pete]

Many point that LPG burning while doesn't make oil dirty (as it is cleaner than gasoline) it combusts at a higher temperature and can lead to oil nitration (HNO3).

this myth was busted. lpg is ~100c less; (measured after valves).
lpg/cng=acea a3/b4 imho, because it may have sulfur=acids which must be neutralised.
i make 13000km/y; i change oil 2x. 25€ wont make me bankrupt....
my exhaust is a bit rusty but no soot.

 

[Zyborg]

As I've still got roughly 3000km before my next oil change (late May or early June) I've been looking closely to 15W40 HDEOs. One of the few US manufacturers that is actually available to me is MAG1. 20eur for 4 quarts (3.78lt).

MAG 1® Premium Conventional 15W-40 CK-4 Heavy Duty Diesel Engine Oil - Mag 1

They are kind enough to provide (most) of the oil ingredients as well as some generic specs. Noack 10%, visc.@100C 15.56 cst, HTHS 4.2 cP, 66 ppm Moly, 1100 ppm Mg. It is dual rated as API SN (alongside API CK-4 and ACEA E9/E7).

What do you think? For this price I can justify to change my oil 2x per year (to swap for a 5W30 or 5W40 in the winter) and keep 15W40 from May till early December (we do not see temps below 5C until January). It doesn't have any synthetic content so it must be either full Group II or either a blend of Group I & II. But I really like the additive package and I think being 0.2 cP thicker as far as HTHS is concered (compared to my current Elf oil at 4.0 cP) it should burn less.

 

[Zyborg]

Hi everyone once again. I've completed ~7660km on this Elf 10w40 oil. Trying to select the most suitable oil for my application I have to mention some findings so far:

1. The oil consumption is caused mostly by the leaky valve stem seals. During cold startup there is the usual whitish smoke caused by condensation. However, as the weather gets warmer, the smoke is still there, albeit less thick. I suspect that oil leaks to the combustion chamber and it smokes until it gets burned. Maybe this is why sometimes is a bit harder to start, while other times (especially when the outside temperature is >25C) it starts instantly. And maybe this is why on hot restarts (e.g., after driving 30mins or so and then stopping for 5mins) the car would jerk. I will check if the spark plugs are oil fouled to confirm my hypothesis. The spark plugs were changed with OEM ones before ~14.000km.

2. Zero oil consumption after 2 long highway trips (in total over 1000km). I drove mostly in cruise control at 110km/h and below 2800rpm. Usually when I traveled at higher speeds (>140kmh, > 4000rpm) I'd see the oil going down ever so slightly.

3. This Elf oil started to turn darker (but it is still pretty clear) at roughly ~7000km. Given the oil age in the pan is roughly 8 months old, I'd say that multiple heat cycles and short city trips are to blame for this. Of course, we are talking for a semi-synth oil.

With all these in mind, could it be beneficial to switch to a part-ester oil or even use ester additives such as Mannol 9929 in the next oil change? I am also considering these oils:

1. Shell Rimula R6 LM 10w40 HDEO, API CK-4 (not dual rated), GTL-based, very low Noack (~6.1%), sulphated ash: 0.95, indicates that is suitable for heavy-duty CNG engines (should resist nitration), very high flash point (250C).

In the German oil-club they even mention that it contains esters, although the FT-IR is not that clear to verify it.

Shell Rimula R6 LM 10W40 - Ölanalysen und Ölanalytik für Motor und Getriebe

Frischölanalyse: Shell Rimula R6 LM 10W40 [URL:https://oil-club.de/index.php?thread/9776-shell-rimula-r6-lm-10w40/] TDS: https://www.transdiesel.com/media/pdfs/20138.pdf Hallo, wie ich finde ein sehr interessantes Sommeröl für Dieselfahrzeuge mit oder…

oil-club.de

My biggest concern for this oil would be seal compatibility. Could it harm my already weak seals? Some people in BITOG mentioned that HDEOs have less strict seal compatibility tests compared to PCMO.

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Could Ashless Dispersants (which for sure exist in this oil) harm my seals?

2. Petronas Syntium 800 15w50 API SL, but is cheaper and I can run it till early November at least.

3. Aral Turboral 15w40 HDEO but dual-rated (API CI-4 and API SL). Higher level of sulphated ash (1.41), unknown additive package.

4. Mag1 15w40 Premium Conventional HDEO, dual rated (API CK-4 and API SN). Should be 100% Group II (claims it is conventional, not semi-synth).

5. Mag1 10w40 High Mileage API SP. My only issue with this is that it contains only 40ppm of Moly.

What would you do in my situation? Replacing the valve stem seals is out of question for now, but given the oil consumption is not a lot, I could try my luck with something to see if it gets better.

I am open to your suggestions.