Engine Oil mixing (same brand)

[Mo Ali]

Hi everyone,

I have a 2018 Toyota Yaris hybrid and am due for an oil change. I have about 500ml of leftover Petronas engine oil from last year. Instead of buying another 5L container, I was wondering if I could buy a 4L pack of Petronas (same brand) and mix it with the old oil, since the engine requires around 4L.

Is it safe to mix the old oil with the new oil? Would it cause any issues?

Apologies for the silly question; car care isn't my forte

[anchorman]

You mean the same grade?   As long as it isn’t contaminated with dirt or moisture it will be fine.  

[Mo Ali]

Yes, the sane grade I meant, apologies.

Where I live the humidity is quite high, now I am questioning my judgement.... probably will consider buying the 5L as dont want to risk the engine for a tenner.

[Stivino]

Use the oil from last year, your engine won't go bang.

[bathtub tom]

The oil in your engine has had a much harder life than the oil in your can for the past year. If your engine hasn't gone bang, why do you think using the oil in the can will do any harm?

[Bernard Foy]

We undrestand your lack of knowledge about cars. Previous posters are correct it wont harm the engine.

[TonyHSD]

No problem at all to use the left overs from previous years as mentioned. 
Petronas 5 litre pack is better value than 4 Ltr and having some extra oil in your shed , garage is always handy. Use the old stock first and add the new stock after so your leftovers are always an year old maximum. 👍

[Mo Ali]

Thats a brilliant idea Tony 🙂 will be using the old one first 🙂 
 

[bonjo]

as long as the oil was stored in a sealed bottle/ container and has full clarity, there'd be no problem.

I always store my leftovers in a smaller bottle so that there is very little air to make the oil go off for 2~3 years.

I also would mix oil if I need to without any worries even from different manufacturers but always use viscocities recommended for the engine. I stay away from mixing fully synthetic with mineral oil unless it is desparate

[Mo Ali]

Thanks Bonjo , the oil is in its original bottle and it has not been opened since last year.
 

[MikeSh]

2 hours ago, Mo Ali said:

Where I live the humidity is quite high

Oil in the engine gets quite a bit of moisture in it anyway from combustion products. It's not a problem unless the engine never gets warm enough to cook it off. Water in fuel is a bit more risky.

I wouldn't even worry about oil in an opened bottle being a problem - it's not hygroscopic like brake fluid.

[Cyker]

If it's not been left open the whole time it's fine to use - Oil has a very long shelf-life, esp. synthetics!

You can apply a bit of common sense to it too - If it smells bad or doesn't flow in a smooth oily way then it's probably gone, but if it has that rich engine oil smell and flows smoothly and is still a very light colour then chances are it's still perfectly fine.

 

[Mo Ali]

1 hour ago, Cyker said:

If it's not been left open the whole time it's fine to use - Oil has a very long shelf-life, esp. synthetics!

You can apply a bit of common sense to it too - If it smells bad or doesn't flow in a smooth oily way then it's probably gone, but if it has that rich engine oil smell and flows smoothly and is still a very light colour then chances are it's still perfectly fine.

 

Thats a brilliant suggestion 🙂

[anchorman]

Some very noble comments but it I maintain, it depends how it’s been stored and if it wrecks his  engine, everybody saying no problem will turn deaf.  It might well be fine, I store oil but I’m very fussy and I check it before using any dregs.  Any doubt and it goes in a tub labelled “oil can only”.  Some suggestions that semi or fully synthetics are better, well what is synthetic oil?  It just so happens that it becomes either when additives are used to enhance it but there is no standard for exactly when ordinary mineral oil becomes semi or fully synthetic so your lesser manufacturers can claim to be something that more ethical companies do not.  It all comes out of the ground and if you saw what comes off the ship, it’s just stinking black mud full of bits of sticks and crud - it’s not called crude for nothing.

[Mo Ali]

1 minute ago, anchorman said:

Some very noble comments but it I maintain, it depends how it’s been stored and if it wrecks his  engine, everybody saying no problem will turn deaf.  It might well be fine, I store oil but I’m very fussy and I check it before using any dregs.  Any doubt and it goes in a tub labelled “oil can only”.  Some suggestions that semi or fully synthetics are better, well what is synthetic oil?  It just so happens that it becomes either when additives are used to enhance it but there is no standard for exactly when ordinary mineral oil becomes semi or fully synthetic so your lesser manufacturers can claim to be something that more ethical companies do not.  It all comes out of the ground and if you saw what comes off the ship, it’s just stinking black mud full of bits of sticks and crud - it’s not called crude for nothing.

Thank you, what engine oil would you recommend?

[Stivino]

8 minutes ago, Mo Ali said:

Thank you, what engine oil would you recommend?

Use the oil that is recommended in your handbook.

[anchorman]

1 minute ago, Mo Ali said:

Thank you, what engine oil would you recommend?

I've got an SDS (Service Data Sheet) for every Yaris except yours so I’d check the handbook and use any reputable brand.  I find Toyota’s own oils to be very good but their checker isn’t working.  Mobil say 0W/20 and their ESP is very good but expensive.  

[MikeSh]

1 hour ago, Mo Ali said:

Thank you, what engine oil would you recommend?

 

1 hour ago, anchorman said:

your lesser manufacturers can claim to be something

I'd NOT recommend getting 5L of stuff you've never heard of from an eBay seller with not much feedback (or from a certain large country over there ---> ).

It might be used cooking oil that's been filtered and coloured to look pukka ...

( PS. Though to be fair, your car might run for years on it. Like petrol there's a bit of snake oil in the advertising.)

(PPS. Has anyone tested snake oil as a lubricant?)

[Big_D]

6 minutes ago, MikeSh said:

 

I'd NOT recommend getting 5L of stuff you've never heard of from an ebay seller with not much feedback (or from a certain large country over there ---> ).

It might be used cooking oil that's been filtered and coloured to look pukka ...

( PS. Though to be fair, your car might run for years on it. Like petrol there's a bit of snake oil in the advertising.)

(PPS. Has anyone tested snake oil as a lubricant?)

Exactly. Think about it. If I was an eBay seller, trying to sell my oil, I want you money, so of course it will work in your car.

Why not spend a few pennies extra to get the genuine oil, rather than possibly having to spend a few hundred pounds to repair an engine. 

[anchorman]

11 minutes ago, MikeSh said:

 

I'd NOT recommend getting 5L of stuff you've never heard of from an ebay seller with not much feedback (or from a certain large country over there ---> ).

It might be used cooking oil that's been filtered and coloured to look pukka ...

( PS. Though to be fair, your car might run for years on it. Like petrol there's a bit of snake oil in the advertising.)

(PPS. Has anyone tested snake oil as a lubricant?)

I have but not in an engine 🤪

[bathtub tom]

34 minutes ago, MikeSh said:

(PPS. Has anyone tested snake oil as a lubricant?)

No, but if you want to milk one, then I'll try it.💀

[Mo Ali]

Handbook says use Toyota's 0W-20. 

[MikeSh]

2 hours ago, Mo Ali said:

Handbook says use Toyota's 0W-20. 

They would say that. Any reputable 0W-20 will do.

[anchorman]

To be fair, it does say you can use another brand of a matching grade.  

[MikeSh]

3 hours ago, anchorman said:

To be fair, it does say you can use another brand of a matching grade.  

Oh yes. I hadn't read the page, I took the posters comment at face value. 😚

Reading it now reminds me that you need to meet the API type* as well as viscosity.

( * IIRC think this can also be an ACEA or similar class. I've not had to pick an oil for several years now, but I remember having a struggle trying to match the small print on the bottle to our 2 cars which had slightly different specs in that respect.)