Older Cars : Normal Motor Oil Or Semi/full syn?

pinolobu

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hi all

I already posted this question on other automotive forums, hope it's ok to repost here.

Older cars better use normal motor oil instead of semi synthetic or fully synthetic?

One mechanic told me that older cars (9 years and older) better use normal oil, rather than semi synthetic or fully synthetic, because the more expensive oils are "too thin."

When I asked another mechanic, he told me the opposite! He said the fact that semi/synthetic has less drag makes it the better choice.

Who's telling the whole truth?

Thanks for any info.
 

vantageX

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This is a bit of a grey area. Both mechanics are telling the truth though not the whole truth.

If you have an old car and you've been using the normal oil recommended by the manufacturer for years, then you should just stick to that oil. The tolerance level in the engine's of old cars aren't that high hence the need for a thicker oil. Most old cars used an oil with 20W/50 viscosity if I'm not mistaken.

If however you rebuild an engine of an old car with new main bearings, piston rings and all tolerances checked, you can (though I wouldn't recommend it in this country) use a slightly thinner oil though not fully synthetic. Even then there is not guarantee that your camshaft and tappets will be able to cope with the thinner oil. And after awhile you'll be wondering why your engine's top end if clacking away.

The 2nd mechanic was right in saying semi/fully synthetic oil has less drag because its thinner but also because its thinner, it will not protect an old engine from wear and tear. Less drag yes but more friction happens cause the pistons and cylinders are not tight (tolerances not high) hence more movement.

You might experience a slight improvement in power when using semi/fully synthetic oil in an old engine but in the long run you're just killing your engine faster. There are other ways to make power.

Best is always to stick to what the manufacturer recommended. The only time you can sway away from this is if you rebuild an engine with competition pistons, camshafts and the works.
 

flushafteruse

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just use thicker oil 20/50 or 15/50 for cars over 6years,
but make sure oil change made in time,that oil also murah maa,you never regret if u always change....
 

kyheng

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Emmm... how to say, I will say the 2nd mech is 'misleading' you. If your engine is 10 years old based on normal wear and tear which the engine rpm always maintain at 2500-3000, with sometimes goes upto 4000, never do a proper top overhaul, you can do 3 test where fully synthetic which claim can do 10000km, semi synthetic at 5000km and normal(lowest) also at 5000km.
Then you will see the results like below:
fully synthetic can last you for 2000 or less and you must top up oil again
semi synthetic can last you for 2500-3500 and you must top up again
normal(lowest) can last until you service your car
This I tested on my 10 year old Iswara last time, using fully, you can feel like your car going to fly. The oil will lost is because they slip thru the piston ring gap
 

TiBuN

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10 years car, using Mobil 1 0w-40, high rev to 6500rpm consistently and oil change at 10,000km. Already did my 5th oil change using this engine oil (previously using minerals and semi-synth). Never top overhaul b4 *touchwood* and engine basically stock. No need to top up oil so far *touchwood* and so far so good! Heheh...

So it goes by saying, depend on your engine.
FYI mine is Daihatsu HD-EG engine.
 

ken12292703

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For example,

0W - 40

The W stands for WINTER. Basically, Malaysia no winter, don't really need to care about this value.

The important part is the back value, viscocity during operation temperature, higher = thicker, lower = thinner.

The blend is important, whether it's mineral or synthetic...

So, 15W 50 and 10W 50 has no different in thickness in operation temperature but the blend might be different depends on the manufacturer.

Please correct if i am wrong... :_:
 

nitrus

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What about newer cars? (not too old cars) ... Wats the diff is I use Fully/Semi Synthetic ? the level of protection issit ? Fully = Better , Semi = Not so ...? :hmmmm:
 

huakenny

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nitrus said:
What about newer cars? (not too old cars) ... Wats the diff is I use Fully/Semi Synthetic ? the level of protection issit ? Fully = Better , Semi = Not so ...? :hmmmm:
fuly syn = 10k km change oil
semi syn= 5k km change oil

however, some brand semi syn can go for 10k km n fuly for 10k km.....the oil grade is different for fuly n semi.....use semi wil be beter....
 

kyheng

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Some company claims that their oil can last for 10000km, but how about oil filter? Can it last for 10000km? And for standard 5000km oil change the filter also cannot use back and the oil colour is black with some sludge. If 10000km.... I don't know what to say liao. The engine end up have to send for full overhaul later instead of top overhaul. Anyway a fully syn oil price is higher than semi by 100%, depend what we want. For me, if not much problem with my engine, I prefer semi syn oil.

Tibun, I think your car have problem already, as new car the oil also will lost abit atleast every oil change. Is hard to believe that your engine oil never lost on a 10 year old engine. Maybe your engine is special type, who knows. But is better that you get a good mech to check it. Just my 2 cents.
 

ken12292703

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Semi synthetic = half mineral + half synthetic...

Synthetic = fully synthetic

Synthetics are not oils, they are chemicals...

A synthetic oil is an oil manufactured for enhanced lubrication performance using the Fischer-Tropsch process which converts carbon dioxide, carbon monoxide, and methane into liquid hydrocarbons of various forms. The carbon dioxide and carbon monoxide is generated by partial oxidation of coal and wood-based fuels. This process was developed and used extensively in World War II by Germany, which had limited access to crude oil supplies. Germany's yearly synthetic oil production reached more than 90 million tons in 1944. It is today used in South Africa to produce most of that country's diesel from coal. There are several companies developing the process to enable practical exploitation of so-called stranded gas reserves, those reserves which are impractical to exploit with conventional gas pipelines and LNG technology.

The majority of oil lubricants are mineral oils, mixtures of refined fractions of crude oil.

Synthetic oils are fabricated by polymerizing short chain hydrocarbon molecules into longer single chain hydrocarbons. Their lubrication characteristics can be adjusted by controlling the spectrum of molecular weights that go into the finished formulation, which usually also includes thickeners.
 

[s]UpErNoVa

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hmm.. my lancer is 25 years old.. i using CASTROL 20W / 50 but everytime i change my engine oil i'll add extra additive to keep my engine run smooth all de time.. all this while running good n well.. :regular_smile:
 

edwin_lcw

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yeah actually use normal black oil is ok oledi n change on time then can oledi .... i know one mechanic told me that he had a customer 20 yrs car .... every 5000 change black oil n one bottle of additive then kau time engine running more nicer than my car ...... haha ..... but its true .....
 

nitrus

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may i ask, what "additives" r u all talking about...?

anyway tnx lonewolf for d good websites...!! :regular_smile:
 

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