Verdict on use of Shell Helix HX8 ECT 5W-40 synthetic oil without a SOHN/COFS

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Verdict on use of Shell Helix HX8 ECT 5W-40 synthetic oil without a SOHN/COFS

Post by bigpete8 »

I'm sure I've seen mention of the ECT oils before as being suitable for the RX8 but within the context of burning sump oil is it okay ?

Shell Helix HX8 ECT 5W-40
Shell Helix HX8 ECT uses advanced emissions-compatible technology that helps to keep diesel particulate filters clean to help maintain engine performance
Benefits:
Helps to extend engine life by protecting against wear, even in the toughest driving conditions
Suitable for all equipment-manufacturer-recommended oil-drain intervals
Low oil consumption for less frequent top-up
For gasoline, diesel and gas engines; also suitable for biodiesel and gasoline/ethanol blends
Specifications: API SN/CF; ACEA A3/B3, A3/B4; MB approval 229.3; VW 502.00/505.00; Renault RN0700, RN0710, Fiat 9.55535-N2 and 9.55535-M2
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Re: Verdict on use of Shell Helix HX8 ECT 5W-40 synthetic oil without a SOHN/COFS

Post by Lucky 8 Racing »

I don’t think there’s been a replacement that’s been shown to be as good as a good quality 2T. Best option is still to use a sohn and fully synthetic.
Low emission oils tend to burn quickly and have a low flashpoint. Ultimately something that when injected into the chamber won’t last half a second in terms of lubricating properties.
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Re: Verdict on use of Shell Helix HX8 ECT 5W-40 synthetic oil without a SOHN/COFS

Post by Lucky 8 Racing »

Also if it’s full of things to keep an DPF clean, and I can’t imagine that they are particularly useful or could possibly be detrimental to a rotary
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Re: Verdict on use of Shell Helix HX8 ECT 5W-40 synthetic oil without a SOHN/COFS

Post by Phil Bate »

Don't confuse flashpoint with how quickly an oil burns, it's just the lowest temperature at which some component of the oil will vaporise to support combustion.

I think the op wants to know if it's safe to use in the sump without an OMP adaptor. The club advice is to stick to mineral oils or semi-synthetic and avoid synthetic. Of course this brings in the never-ending debate of what synthetic means and whether the oil in question is a true synthetic, and of what type. Oilman posted somewhere recently a selection of oils on OPIE that are billed as fully synthetic but would likely be fine to use in the rotary due to their method of manufacture, I will try and find it when I have time.

Personally (and this is my own personal view, I stress) I wouldn't have a problem with the suggested oil or many other synthetics (depending on how they were made) even without a Sohn adaptor, but as always it's an 'at your own risk' decision if varying from the usual advice.
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Re: Verdict on use of Shell Helix HX8 ECT 5W-40 synthetic oil without a SOHN/COFS

Post by warpc0il »

To add to Phil's response, there are a number for factors unique to the rotary which impact what may or may not be, a suitable oil.

The Renesis injects oil into the combustion chamber, which no 4-stroke engine oil was ever designed to do*.
Having been injected in to the chamber, the oil has to provide good lubrication and then burn, without leaving carbon deposits especially in the area of the seals.

Even that gets complicated as it's been proven that sustained running at high temperature/revs can clean and remove "soft" carbon build-up, but is less successful against "hard carbon"; so even the nature of the deposits matter. Lots of scientific papers have been written on this, most regarding piston engines, though the chemistry is the same, and some even mentioning rotaries.

Anyway, it was the deposition of hard carbon that caused Mazda to issue the statement not to use "Synthetic Oils" in the Renesis - the label being in quotes as Japan has a different definition of "Synthetic Oil" compared to what most western oil companies use on their packaging.

Talking about seals, the rotors have (lets call them rubber) side seals, that have no equivalent in a piston engine, and these seals could react badly; soften/harden/swell when in contact with oil additives to which they were never tested, especially at the temperatures that the rotors run. Such deterioration may (or may not) be immediately apparent and could also be triggered by switching to an inappropriate oil even when using a Sohn/COFS, as the other side of the seal is holding against sump oil.

The whole question is a minefield.

We know that mineral-based conventional engine oils, that haven't changed in the last ten years, should be safe in the Renesis.
Even some of these, and certainly later products, may have been tweaked to provide better performance, long-change cycles etc, in ways that don't help our cars.
Even later products would have been designed with absolutely no consideration as to what they might do in a Renesis - why should they - especially if they're not even listed by the manufacture for use in an RX-8?

Random oil selection is now like trying to get across that minefield on a pogo-stick, you might be lucky....

* there are a couple of special "Rotary oils" that have been developed to do this but we're looking at off-the shelf stuff.
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Re: Verdict on use of Shell Helix HX8 ECT 5W-40 synthetic oil without a SOHN/COFS

Post by bigpete8 »

Phil Bate wrote:
Wed Oct 16, 2019 9:41 am
Don't confuse flashpoint with how quickly an oil burns, it's just the lowest temperature at which some component of the oil will vaporise to support combustion.

I think the op wants to know if it's safe to use in the sump without an OMP adaptor. The club advice is to stick to mineral oils or semi-synthetic and avoid synthetic. Of course this brings in the never-ending debate of what synthetic means and whether the oil in question is a true synthetic, and of what type. Oilman posted somewhere recently a selection of oils on OPIE that are billed as fully synthetic but would likely be fine to use in the rotary due to their method of manufacture, I will try and find it when I have time.

Personally (and this is my own personal view, I stress) I wouldn't have a problem with the suggested oil or many other synthetics (depending on how they were made) even without a Sohn adaptor, but as always it's an 'at your own risk' decision if varying from the usual advice.
The generic selection based on my car reg from Opie does suggest that oil in its 5w/30 guise is suitable so don't see why 5w40 wouldn't be.

I understand what Dave is saying but unless you are sticking to something tried and trusted then it's always going to be a bit of a gamble (and no guarantee the formula of that oil remains constant)

I was just musing as that oil would seem to be more suited (I did raise this in an older post but that went off on different tangent)
Who knows I may even try it out once I exhaust my stock of Wilko oil... :)
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Re: Verdict on use of Shell Helix HX8 ECT 5W-40 synthetic oil without a SOHN/COFS

Post by warpc0il »

Does Shell certify that oil for the RX-8 or is the Opie site just matching against 5w/30?
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Re: Verdict on use of Shell Helix HX8 ECT 5W-40 synthetic oil without a SOHN/COFS

Post by bigpete8 »

Good question. From looking again at the results it is entirely possible as all are 5w/30

Having had another browse of oils I can see there is a semi-sythetic 5w 40 - presumably most would view this as more suitable?

Shell
Shell Helix HX7 5W-40 is a semi-synthetic oil which helps to keep engines clean and running efficiently by helping to prevent the formation of sludge and engine deposits. It is suitable for a wide variety of modern vehicles driven in demanding traffic conditions. Shell Helix HX7 helps to prolong the engine life of modern vehicles in demanding daily traffic conditions by protecting against wear. Shell Helix HX7 can be used for gasoline engines, diesel engines (without particulate filers) and gas engines, and it is also suitable for use with biodiesel and gasoline/ethanol blends
Benefits:
Makes use of both synthetic and mineral base stocks to achieve higher performance levels than can be formulated from mineral oils alone
Helps to extend engine life by protecting against wear, even in daily traffic conditions
For gasoline, diesel and gas engines; also suitable for biodiesel and gasoline/ethanol blends
Specifications: API SN/CF; ACEA A3/B3, A3/B4, JASO SG+, MB approval 229.3, VW 502.00/505.00, GM LL-A/B-025, Renault RN0700, RN0710, Fiat 9.55535-N2 and 9.55535-M2 (meets the requirements of)
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Re: Verdict on use of Shell Helix HX8 ECT 5W-40 synthetic oil without a SOHN/COFS

Post by PeteH »

I use HX7 10W-40, and I think a few others do as well.

If I wasn't racing, and used my car in winter, I'd probably drop to 5W-40 or 5W-30.

It's all guess work though... :?
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Re: Verdict on use of Shell Helix HX8 ECT 5W-40 synthetic oil without a SOHN/COFS

Post by AndyBrad »

Here we go again.

Personally I think its mostly bobbins and scaremongering. For those with an s1 with no oil pressure increase. Then it can not be argued against that a 40 weight oil will be preferable. I personally (working in oil and gas and specifying seals) think that there should be any issue with synthetic oils and orings in the engine. Additives (which could be in both synth and semi are a different matter)

Its been proven that a 40 weight oil has better bearing protection than a 30 weight oil with regards to bearing life.

5w is still a lot thicker than 40 weight at temp so id suggest it is preferable.

With regards to carbon I don’t think anyone can comment as to which would burn better?
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Re: Verdict on use of Shell Helix HX8 ECT 5W-40 synthetic oil without a SOHN/COFS

Post by warpc0il »

I use H7 10w40 as a personal choice, even with a sohn.

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Re: Verdict on use of Shell Helix HX8 ECT 5W-40 synthetic oil without a SOHN/COFS

Post by Phil Bate »

AndyBrad wrote:
Wed Oct 16, 2019 3:02 pm
...
Its been proven that a 40 weight oil has better bearing protection than a 30 weight oil with regards to bearing life.

5w is still a lot thicker than 40 weight at temp so id suggest it is preferable.
For every day use it's probably equally if not more important to change the oil regularly than worry too much about the viscosity, which doesn't stay the same for long with the amount of shear wear a rotary creates. A 10w40 is starting from a higher rung of the ladder but will soon degrade as it's chopped up through the stationary gears. Especially if it's a cheap 'semi-synth' chock full of viscosity modifiers.
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Re: Verdict on use of Shell Helix HX8 ECT 5W-40 synthetic oil without a SOHN/COFS

Post by Ryan Rotary Performance »

Phil Bate wrote:
Wed Oct 16, 2019 4:33 pm
For every day use it's probably equally if not more important to change the oil regularly than worry too much about the viscosity, which doesn't stay the same for long with the amount of shear wear a rotary creates. A 10w40 is starting from a higher rung of the ladder but will soon degrade as it's chopped up through the stationary gears. Especially if it's a cheap 'semi-synth' chock full of viscosity modifiers.
The amount of times I've explained this, I must just do an audio recording and carry it around with me :)

Cheers phil, nice for someone else to recognise this too :thumright:
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Re: Verdict on use of Shell Helix HX8 ECT 5W-40 synthetic oil without a SOHN/COFS

Post by AndyBrad »

Phil Bate wrote:
Wed Oct 16, 2019 4:33 pm
AndyBrad wrote:
Wed Oct 16, 2019 3:02 pm
...
Its been proven that a 40 weight oil has better bearing protection than a 30 weight oil with regards to bearing life.

5w is still a lot thicker than 40 weight at temp so id suggest it is preferable.
For every day use it's probably equally if not more important to change the oil regularly than worry too much about the viscosity, which doesn't stay the same for long with the amount of shear wear a rotary creates. A 10w40 is starting from a higher rung of the ladder but will soon degrade as it's chopped up through the stationary gears. Especially if it's a cheap 'semi-synth' chock full of viscosity modifiers.
and an excellent reason for going to a proper full synth!!
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Re: Verdict on use of Shell Helix HX8 ECT 5W-40 synthetic oil without a SOHN/COFS

Post by bigpete8 »

Apologies to any one offended by another oil topic 🙄
The synthetic question was partly why I quired the use of hx8 but also because I was looking for a 5w40 oil though now know their is at least one semi synthetic in that grade.

In all honesty as I have a stock of something I will continue frequent changes with that then maybe think on something for next summer onwards
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