Can combination of synthetic and non synthetic engine oil cause damage?

[Quest]

I am not much of an expert in this...can topping up with synthetic engine oil (to non-synthetic engine oil) do any harm to the engine? I am asking this on behalf of a friend that had damage to his crank (so we suspect)....no noise on idle, but gets worse when being driven. Engine will be stripped this week to evaluate extent of damage.

He said the engine light 'flashed' and there was a thud.....there was apparently around 1.5l of engine oil in the engine...he also said that when vtec is engaged, the engine sucks up 1.5l of engine oil (so he was told).

[Crapdaz]

It shouldn't as i've been mixing cause i've had left overs from different bottles since oil changes. Whats the mileage on the car? if < 5-10k then no don't use it, as the engine hasnt been run in yet.

How'd your friend damage the crank?

[tron07]

oil starvation does more damage to the engine then mixing synthetic with mineral oil. Mixing oil negetes the benefits and addictives in the oils, but it will not kill the engine, unless you use mineral oil + syntethic and interval oil change is following synthetic change schedule.

Euro engine require around 4.2 liter of oil....

[aaronng]

He said the engine light 'flashed' and there was a thud.....there was apparently around 1.5l of engine oil in the engine...he also said that when vtec is engaged, the engine sucks up 1.5l of engine oil (so he was told).
If there was only 1.5L of oil in the engine when it was drained and pulled apart, then the cause of his engine failure is the lack of oil. Not mixing.

There is nothing wrong with mixing oils, except for a handful of specialised oils that specifically tell you not to mix.

[Quest]

If there was only 1.5L of oil in the engine when it was drained and pulled apart, then the cause of his engine failure is the lack of oil. Not mixing.

There is nothing wrong with mixing oils, except for a handful of specialised oils that specifically tell you not to mix.

I did some reading last night again on the topic and found this
http://www.ozhonda.com/forum/showthread.php?t=98677&page=2

"According to the service manager Honda Australia don't recommend the use of fully synthetic oil because it burns off too easily and recommended me to use a blended semi-synthetic type next time round"

We are unsure what oil was used prior to incident as the car had just come back from the shop with the ffg mods done

Skunk2 stage 2 cams ( intake and exhaust)
Skunk2 cam gears
Skunk2 titanium retainers
Skunk2 titanium valve springs
Ported and flowed head
Hondata heat shield gasket
Spoon spark plugs
Honda RBC intake manifold
Dastek UniQ + vtec controller

If for argument sake (from above link and comment), a synthetic oil was used by the shop...and then another synthetic brand used to top up....could that cause a 4.2l-1.5l = 2.7l loss in 3 days? How long does it take for synthetic oil to "burns off too easily"

There are no engine leaks and the engine was not smoking prior.

[tron07]

I use synthetic oil and never top up the oil before... cause it never "consume/burn" any engine oil

[aaronng]

I did some reading last night again on the topic and found this
http://www.ozhonda.com/forum/showthread.php?t=98677&page=2

"According to the service manager Honda Australia don't recommend the use of fully synthetic oil because it burns off too easily and recommended me to use a blended semi-synthetic type next time round"

Nope, synthetic does not burn more than mineral or semi-synthetic. Honda Australia says that you can use aftermarket oil as long as it is better than Honda's FEO (and almost every synthetic is better!). The oil burning could have been caused by blowby, pushing the engine oil into the PCV and then into the combustion chamber to be burnt.

[aaronng]

We are unsure what oil was used prior to incident as the car had just come back from the shop with the ffg mods done

Skunk2 stage 2 cams ( intake and exhaust)
Skunk2 cam gears
Skunk2 titanium retainers
Skunk2 titanium valve springs
Ported and flowed head
Hondata heat shield gasket
Spoon spark plugs
Honda RBC intake manifold
Dastek UniQ + vtec controller

If for argument sake (from above link and comment), a synthetic oil was used by the shop...and then another synthetic brand used to top up....could that cause a 4.2l-1.5l = 2.7l loss in 3 days? How long does it take for synthetic oil to "burns off too easily"

There are no engine leaks and the engine was not smoking prior.
2.7L loss in 3 days is very difficult to achieve unless you were missing a gasket off the engine. Since the Euro wasn't leaking oil, I don't think that it was being burnt that quick. I reckon he didn't checked his oil level since his last oil change.

With all those mods, what was the redline of the Euro?

[tony1234]

I use synthetic oil and never top up the oil before... cause it never "consume/burn" any engine oil
Me too.

[Min988]

Me too.

Same I never had to top up ever and I've been using the stuff for ages but the dealer's service centre was pretty serious and concerned about it, they even wrote it on my invoice.

[tony1234]

Same I never had to top up ever and I've been using the stuff for ages but the dealer's service centre was pretty serious and concerned about it, they even wrote it on my invoice.
The service centre i go to said a similar thing but didn't make a big deal about it like yours did.All mine wrote on my invoice was"customer supplied engine oil".How many kms. you done?

[EuroAccord13]

I have very similar modifications to your mate's car and I only burn up a little less than 1L of engine oil every 5000kms.

To burn up so much is too extreme if there are no signs of oil leaks on the walls of the engine.

[Min988]

The service centre i go to said a similar thing but didn't make a big deal about it like yours did.All mine wrote on my invoice was"customer supplied engine oil".How many kms. you done?

I'm up to 42000km on my dial but I started using full synthetic since 25000km's. I'll still be using what I want to use.

[tony1234]

I'm up to 42000km on my dial but I started using full synthetic since 25000km's. I'll still be using what I want to use.
I've been using full synthetic since 10k.Now have 47k.

[jdm_b16a]

Firstly, it is a myth that you can't use synthetic oils from Day 1. Many people switch to synthetic oils after the first service.

This topic of "Mineral vs Synthetic" has been on the web for as long as the Internet has been 'up'. There are two sides and always will be.

Synthetic oil doesn't break down anywhere near as fast as mineral oil. With average driving mineral oil is changed every 5-10K or every 3 months. Synthetic can be used for 12 months without change. In fact, I replaced my engine oil with synthetic, after the first service (back in 1994) and didn't change it for a long time (several years). I don't recommend that but that's what happened. The car ran fine for over 10 years before I did the B16A upgrade. In fact I never changed my gearbox oil in all that time and it was still golden when dropped from the original engine/gearbox during the changeover!

I would be looking at the mods done to the car as the source of the problem, not the oil.

Mixing mineral and synthetic just negates the advantages of the synthetic. It would not damage an engine. The fact that the engine only had 1.5L suggests the engine oil wasn't added correctly, or wasn't topped up. If you do a full drop and refill, the levels will be high until you run the engine and fill the lines, the oil filter, etc. Then you top up again and check the dipstick. You might have to do this once or twice to get the "full" level.

Anyway, too many variables here to give a definitive answer.

Shame the engine broke, especially after all that work!

BTW, you are entitled to supply your own filters and oils when having your car serviced, which is a good thing given the full RRP the service centres charge for the same products you can by a significant discounts at the retail chains like Repco or SCA.

Peter

[tron07]

not recomended to use synthetic from day 1..... use it after 10k so the engine is sufficiently "run-in"

eer... Gearbox oil... good luck with your gearbox if its an auto

[Quest]

Thanks for the very very helpful info guys,.....I would not have had the variety of responses in ZA forums.....thanks again..... awaiting for my mate's car to be stripped today inorder to identify fault..and will report back