thicker oil or better oil contents

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Originally Posted By: GSL
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You can use either oil weights but the 5w-30 is the preferred oil to use for best overall results.There is a misconception that if you have high milage, that you need thicker oil due to "wear" tolerance between parts.This is generally incorrect,since getting lube to the moving parts is the most critical.Thicker oil is slower to get in between moving parts, as well as having less base oil per qt.[Main lubrication ingredient.] due to required additional additives required to make a wider 0w-40 multigrade or any other "thicker" oil(Resulting in less base oil per quart.).
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In my earlier days in tech training, we took a extremely high mileage{More than 1/4 million miles.) Ford Taurus V6 & ran multiple test with different weights of oil.The results were eye opening to say the least.With the thicker straight 30w weight as well as even the most popular 10w-40 multigrade, the results were much worse (Less pronounced with 10w-40.)than with the factory recommended 5w-30 oil. H.P. & fuel efficiency was lower,emissions higher, and idle rougher. In fact, the straight weight would cause a smog test to possibly fail due to to both high emissions & unstable idle speed.
So no matter how many miles you have on the vehicle, it is best to stick to the factory spec. grade of oil{Unless you have a very high consumption of oil, for which you can as a last resort make a single switch up in multigrade oil type or use an oil additive[STP or any stabilizers.] to do the same.
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I'm wondering why you keep mentioning "weight" and "weights" of oil. What does weight have to do with oil? No such thing as "straight weight" oil.
 
Huh, we are from diffarent parts of the world, and english language has its own differences in meaning.

For me, It is obvious that GSL use "staright weight oil" as synonym for "single grade oil" - eg. opposite to multigrade oil.

I think he wanted to say "In fact, the single grade oil would cause a smog test to possibly fail due to to both high emissions & unstable idle speed."

Interesting and usefull information.
 
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Don't forget asking about synthetic. Posts there also.

Not knowing the W stands for winter instead of weight is not grammar or spelling.
 
I suppose there is lot of people here that you could put in a "thinner is better than thicker".

For my common rail diesel 1.4 HDi (Citroen C3) - PSA (Peugeot/Citroen) recommends oils from 9.8 cSt to 14 cSt @100 C - for whole Europe (from Norway to Greece).

I use (last four OCI) oil that is ~10.2 cSt @100 (ACEA C2) - despite the engine have passed more than 300,000 km. Oil consumption is about 1.5 L for 15000 km (~9000 miles) - at a same rate with 5W-30 (ACEA C2) as with previous 5W-40 (ACEA A3/B4, ACEA C3).

Furthermore, average speed (for ~15000 km) of this city car is 25 km/h, average diesel consumption is 4.6 L/100 km)- according to board computer.

I`d say that my chosen oil - is thick enough
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Anyhow, BMW 318d DPF, 2009. from Chech Republic

Originally Posted By: ilyamiee
Hi everyone,
I have a 2009 BMW 318d with 2 liter N47 engine, with quite some mileage: 175k. Stock one, DPF is in place, so LL-04 and Euro-5. Last 50k I use Castrol Edge titanium FST 5w-40 due to it high viscosity.

What would you suggest, please?


I`d try Liqui Moly


TopTec 4100 5W-40
https://pim.liqui-moly.de/pidoc/P000322/3700-TopTec41005W-40-24.0-en.pdf
TopTec 4600 5W-30 https://pim.liqui-moly.de/pidoc/P000327/3755-TopTec46005W-30-28.0-en.pdf

Bet that any will do (great) - but I would try thinner first.

Second great choice, (also from Germany) would be... e.g - Fuchs

5W-40 Titan GT1 http://www.repuestosmercedes-benz.com/PI_TITAN-GT1-5W-40_e.pdf
5W-30 Titan GT1 Pro C3 http://www.generaloils.net/PI_TITAN-GT1-PRO-C-3-5W-30_e.pdf
5W-30 Titan GT1 Pro Flex http://www.generaloils.net/PI_TITAN-GT1-PRO-FLEX-5W-30_e.pdf


I`d change these oils in no more than 15000-20000 km (5W-40 12000-15000 km).
 
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I have a Focus with a 1.5TDCi which is related and based heavily on the DV4/DV6 PSA engines.

The last few analysis's I've had done show significantly more wear materials in the oil with thinner 30 grades B5) compared to thick 30 weights >12cst @ 100°c (0w30 or 5w30 meeting A3/B4).
The wear materials are still very low but are significantly higher. My engine seemingly uses no oil on either oils but is quieter and smoother on the thicker oils. I haven't noticed any loss in power or fuel economy either.

I'm waiting to do 5k on the current fill of Mobil1 Turbo Diesel 0w40 to see what it's analysis looks like. The engine certainly is very smooth running on the M1 but I'm uncomfortable with the high SAPS of 1.3%. That said the limit for the Ford 913D oil that is specified is 1.3% so unsure why it bothers me so much.
 
These things go on forever - But there was no Mobil Valdez. Further, the biggest environmental disaster ever is never talked about - when a thug sent troops into another country to blow off wellheads - far more oil spilled, burned, and the subsurface asset destroyed ... it was malicious intent - not an accident ... (but not my backyard as they say) ...
 
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