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Old 1st May 2007, 21:47   #1
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Default Difference in diesel and petrol engine oils

Hi,I had sent my Palio 1.6 S10 for service at an auth.Fiat service centre.Service bill sent by them has Rs 633.20 charged for 4 lts.Diesel Engine Oil.When enquired,they assured me that it's due to some computer error and they have filled right engine oil.But I doubt their claim as bill has clearly mentioned part no. for diesel engine oil (FIATOILDSLL) and particulars given as Engine Oil Diesel.Car too is not driving like a newly serviced vehicle and appearing even sluggish.I want to know,is there some big difference in petrol and diesel engine oils,and can I check it by any means.What if they have really poured Diesel Engine Oil in my petrol engine,can it harm the engine?http://www.team-bhp.com/forum/images/smilies/mad.gif
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Old 1st May 2007, 22:51   #2
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Yes, there is a big difference in petrol engine lubes and diesel lubes.

In short run interchange won't do any harm, but in long run, they will harm the engine. Confirm the oil is right and get it changed if in doubt.
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Old 1st May 2007, 22:53   #3
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How would it be confirmed What Oil went in..!

Is there some test or what..!
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Old 1st May 2007, 23:00   #4
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Visual test after the oil has run for some time is almost impossible. (Only way is to check the container - but those guys are not likely to give it to you). To confirm, only way is lab test.

Another crude method will be using a two glass rods of same dimension and take a sample from a similarly used petrol lube. Dip the glass rod in both and let it run down to other end by holding them at same angle. Compare the time. Also use the filter paper (such as newspaper) and put a couple of drops and see how time it takes to spread out and what pattern it spread outs.
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Old 1st May 2007, 23:06   #5
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Diesel oil is much thicker than the petrol oil in order to hold the higher CR .. Also diesel oil's produce a lot of dust on combustion .. They also have anti-foaming agents which are required in diesel engines and not in petrol engines .. However this shouldn't make much of a difference .. I know a friend who runs diesel engine oil in his TCed car and he hasn't had any problems yet .. However , if you want its advisable that you flush the oil once and get 20W40 put in just for your satisfaction ..
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Old 2nd May 2007, 00:23   #6
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Actually most multigrade oils are okay for both diesel and petrol.
When you have a petrol engine oil which meets the highest specifications of API-SM for petrol, for example the synthetics in our market, those oils meet very low diesel oil specifications, eg API-CF4
http://www.burkeoil.com/pdf/oilguide.pdf
http://www.api.org/certifications/en...lGuide2006.pdf
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Old 2nd May 2007, 00:58   #7
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Quote:
Originally Posted by tsk1979 View Post
...a petrol engine oil which meets the highest specifications of API-SM for petrol, ... meet very low diesel oil specifications, eg API-CF4...
Ummm... so are we here saying that the very best petrol engine oil can only meet the lowest spec diesel oil? In other words the best of the petrol engine oil can at best be a poor substitute for diesel oil?

If my understanding is correct then has that got to do with the general viscousity of the oils? The diesel engine oil being much more viscous? In that case again won't that be harmful to a petrol engine?
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Old 2nd May 2007, 02:01   #8
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Can I use Mobil 1 in my verna diesel? Will it be ok?
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Old 2nd May 2007, 05:33   #9
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Quote:
Originally Posted by Zappo View Post
Ummm... so are we here saying that the very best petrol engine oil can only meet the lowest spec diesel oil? In other words the best of the petrol engine oil can at best be a poor substitute for diesel oil?
Yes!
Quote:
Originally Posted by Zappo View Post
If my understanding is correct then has that got to do with the general viscosity of the oils? The diesel engine oil being much more viscous?
In a very partial restricted way, yes!
But I will explain further.
Quote:
Originally Posted by Zappo View Post
In that case again won't that be harmful to a petrol engine?
[/quote]
Not really. Unless you use a very heavy bulldozer oil, it won't harm. But it will certainly spoil the fuel economy.

That being said, why do we use engine oil at all?
  1. To prevent moving metal surfaces that rub against each other from tearing themselves apart by coating them with a continuous film of oil.
  2. To convect heat away.
  3. To hold in suspension the silica and acid waste products of combustion, until the next oil change.
  4. To clean the engine of such chemicals and prevent high-temperature oxidation.
API classifications are different for petrol and diesel engines:
For Spark ignition engines, listings start with 'S' (SG, SH, SL, SM, etc.).
For Compression ignition engines, listings start with 'C' (CF, CG, CH, etc.).

Diesel oils have higher detergent levels. Useful for flushing the engine. But let me caution with a caveat here:

The gunk/carbon deposits an old engine help seal piston rings, hydraulic valve lifters and sometimes even the gaskets at the cylinder head, various covers, oil sump and cylinder block, esp. where the gaskets are thin.

Some high-mileage engines worked fine until they were flushed clean. Flushing clean allowed the combustion-product blow-by to get past the cleaned oil-scraper piston rings. This blow-by contaminated the oil and wrecked the connecting rod bearings. Discussed blow-by with Rohan L. only the day before.

Experimenting with engine oils can wreck your engine, if you use the wrong oil. The safest bet is to stay with the oil recommended in the manufacturer's book.

Ram
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Old 2nd May 2007, 11:13   #10
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Agree With Ram Sir why take a chance anways.Just go and get the oil change done again right in front of u asap and drive with a peace of mind[]
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Old 2nd May 2007, 12:03   #11
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ram made it all clear
Another note I would like to add is the modern diesel engines are very very sensitive to engine oil.
In India most service books recommend API-CF4, but as soon as we get E-IV, you will see engines requiring API-CH or API-CI
In such engines if you put API-CF4 oil(which most synthetic oils are) you will ruin the engine.
I try to put atleast API-CG in my indica, but mostly I have started putting a cheap mineral oil which is API-CI (Castrol GTX diesel).
I havent seen a synthetic oil which meets API-CI in the market.

I have also heard the diesel engine oil is "a little too good" for petrol due to detergent properties and may lead to leaking etc., so always use a petrol oil which meets your standards.
If a petrol oil meets API-SM standards its rare that it will go beyond API-CF
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Old 2nd May 2007, 13:14   #12
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Quote:
Originally Posted by Sam Kapasi View Post
Can I use Mobil 1 in my verna diesel? Will it be ok?
NO , not unless you want to go the Pimp My Ride way and pimp your verna with High Compression Pistons , Forged Conrods and the likes ..

Like I mentioned earlier Diesel Engine oils contain anti-foaming agents which are required by diesel engines and not by petrols .. Also , in order to hold up the higher Compression Ratio of the diesel engines the oil has to be more viscous in case of diesels .. Adding petrol engine oil to a diesel engine would only have its effects in seeing you with your car shouting out " I want to Pimp My Ride Now " ..
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Old 2nd May 2007, 13:28   #13
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Sam, you can use Mobile 1 in your diesel Verna. Mobile 1 meets the specification s given by Hyundai. Incidentally, Skoda recommend only 100% synthetic oils for the TDi's. They use Mobile 1 and Shell at their A.S.S.

Quote:
Adding petrol engine oil to a diesel engine would only have its effects in seeing you with your car shouting out " I want to Pimp My Ride Now "
Mclaren, it depends on the construction of the engine. Trucks etc need a different type of oil. Most diesel family saloons accept the same grade as their petrol counterparts. I had a similar question 3 years ago when I did my first oil change on the Skoda ( Linky (Oil for a Diesel). Being new to diesel at the time, I wasn't sure about this. I did send an email to Mobil and they replied that the regular Mobil1 is best for the Octavia diesel engine.

Always go by the actual specs given in your user manual. Most Synthetics will meet or exceed those mentioned by them.

Last edited by Rtech : 2nd May 2007 at 13:33.
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Old 2nd May 2007, 13:31   #14
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rtech I believe the issue is similar to the fact that 87 octane fuel can be put in modern petrol engines, but if you put 91 octane its better, and 93 is better than 91 etc.,
I do not know about mobil 1, but the castrol edge synthetic oil is API-CF4 which is the "minimum" specification required for Verna/Elantra etc.,
Does somebody have a Mercedes C class diesel(new) service book? What do the minimum specs say there? I will be shocked if its not CH.
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Old 2nd May 2007, 13:36   #15
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Quote:
Originally Posted by Rtech View Post
Sam, you can use Mobile 1 in your diesel Verna. Mobile

Mclaren, it depends on the construction of the engine. Trucks etc need a different type of oil. Most diesel family saloons accept the same grade as their petrol counterparts.
That means we wont be seeing sam after all in " Pimp My Ride " ..

Robin thanks for pointing that out .. Wasn't aware of the skoda and hyundai specifications for diesel engine oils .. Anyone aware of the specifications for the swift and the elantra ??

Quote:
Originally Posted by tsk1979
I believe the issue is similar to the fact that 87 octane fuel can be put in modern petrol engines, but if you put 91 octane its better, and 93 is better than 91 etc.,
Not necessarily , unless you CR is high leading to the use of higher octane fuel .. On a stock CR using higher octane would only lead to the engine running a little smoother with no increase in performance ..

Last edited by mclaren1885 : 2nd May 2007 at 13:38.
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