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diyiggy 30th June 2019 11:46 AM

Snake oil for cars engine
Greetings audio fellows,
I readed very goods inputs in John's long preamp thread about oil grades and car engines.

What about the real agging of the oil in the diesel engines from our cars please.

My car manual says to purge engine oil every 20 000 kms or every two years.

What about synthetic oils as the 5W40 if I onlt drive 3000 kms a year ? Should I purge the oil's engine every year ? Why ? Humidity? EGR that dirsts the top of the engine faster ? Towns use ? More pollution from gaz exhaust? Etc...

Help me please debug the truth please in that particular case. Is it for marketing reason as buying oil or for enginnering true reasons?

Many thanks for your futures inputts

Tjj226 30th June 2019 01:06 PM

Well what I like to do with my car is change the oil before it goes completely black. I do not like waiting until the oil is completely fouled before changing it because that means my car ran with dirty oil and was subjected to more wear and tear than need be.

On MY car (99 miata), I have found that if I change the oil about every 3000 miles the oil that drains out is a really dark redish color. AKA its close to turning black.

I also don't play around with oil weights. I put in what the manufacturer recommends, and I recommend you do the same.

I don't play around too much with the quality of oil either. I buy what ever name brand oil is on sale or is otherwise cheaper. IMO buying oil that is half the price of the expensive stuff but doing oil changes twice as often will almost always yield better results.

Here is what I would suggest. Get your oil changed and then ever 1000 km crack the bolt on the oil pan just enough to let some oil drip out. Make a note of the color, then tighten the bolt back down. Keep repeating the process until you notice the oil is black or near black. From then on, I would change the oil at what ever that interval turns out to be.

diyiggy 30th June 2019 01:34 PM

Thank you for your inputt.

The Miatta has a solid engine, it's near a no problem car from what I readed :), it worths to change oil more often, it became a collector car (at least I dunno with the brandnew model which has a slighty different motor from the readed reviews)!

I have a diesel engine and diesel powered engines have their oil being black in few kilometers (less than 1000 km), so not really an indication of real aging for my car.

Yep I use the 5w40 oil and the index given from constructor in my model car manual.

Question is : does time change oil quality and degrade diesel engines after one or two years when driving few kilometers per years as my yearly 3000 km ?

As the engine is in sealed circuit, does humidity apply as brakes fluid ?
When driving really few does an older oil becomes less efficient to lubrificate piston cylinders and so on when starting the engine ? I readed synthetic oil catchs less humidity than the old mineral oils!
Does the town driving a factor to change faster the engine oil (well a diesel engine is not running as fast as a fuel engine - Most of the time diesel cars break from the engine surrounding : gear, turbo, diesel pump, transmission).

I'm going to clean the EGR valve and the air admitting pipe (collector is unluckily to hard to remove without time as I have not a private garage) but I really wondering if yearly or every two years fresher oil is better for the top of the engine (common piezo injection ramp, admission valves, etc ?) My car is 140 000 kms and should break before 200 000 Km due to some others causes (turbo as said, diesel pump mainly but also gears box) and will costs much than purchase a second hand car with less kilometers.

mountainman bob 30th June 2019 03:14 PM

Having been mechanically inclined my entire life (personally/professionally)

I can unequivocally state (without ABX testing) that no internal combustion engine will suffer from oil that is too fresh.......just change it.

And if your way under mileage at 2 yrs and those miles were easy driving 3 yrs is not a rotella t (Dino) or t6 (synthetic) are good diesel oils. (In the reco’ed vis of course)

kevinahcc20 30th June 2019 03:15 PM

I take it your car does not have an oil life monitor system...if it does this is the best way of scheduling oil and filter changes. Otherwise follow the manufacturers recommended oil and filter service schedule and use an oil with an API service rating equal to or higher than the manufacturers recommendation. One caution on diesel oils, newer formulations designed for compatibility with aftertreatment systems and low sulfur diesel fuel are not necessarily backward compatible with older diesel engine technology.

diyiggy 30th June 2019 03:30 PM

Thank you to both of you,

My car has a warning oil syst that lights wether the parameter comes first, time or kilometers since last purge following constructor recommendation. Anyway I change the oil filter eactime I change oil cause it costs almost nothing on my car model and it removes the 0,5 liters of the old oil.

diyiggy 1st July 2019 11:52 AM

Btw, is it true pre purge cleaner additives can clean the motor for less exhaust polution ? Or just a gadget and better to change the oil filter when swaping the engine oil instead?

mountainman bob 1st July 2019 12:11 PM

Everything you could ever want to know about oil is on this website(no relation!) A Review of Mineral and Synthetic Base Oils - Bob is the Oil Guy

diyiggy 1st July 2019 12:15 PM

Awesome ! Thank you so much :)

korpberget 1st July 2019 12:23 PM

Do not use oil additives. If you want to clean the innards of your engine do it the proper way. Or do as an old school mec like me does. Drain the oil, add right amount of diesel instead of oil and run it on idle until its warm. Drain and change filter. Add new oil. If this sounds dodgy - than don't.

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