Which oil?

bennyboy · Post by **bennyboy** » Thu Oct 03, 2013 10:58 am

I used 10-40 semi synth for nearly 100k miles, engine went on to save a 5th gen even with 180k on it as it was still very healthy.

The new engine runs fully, but obviously that's starting from scratch with new bearings, gaskets, seals etc so makes more sense.
TBH, if you have a decent amount of miles on your engine, as 99% will do by now, 10-40 semi is going to be just fine

Stevelar_granolar · Post by **Stevelar_granolar** » Thu Oct 03, 2013 4:25 pm

Rocking 10-40 semi with 145,000 still going strong!

Space1999 · Post by **Space1999** » Thu Oct 03, 2013 11:21 pm

If you want your engine to wear out faster, have less MPG and less BHP, and produce more sludge and potentially higher emissions, the semi-synth is fine! This is not my opinion, this is scientific, empirically measurable, fact.

Given that you can get full synth from places like Opie Oils (with whom I have no connection, by the way) for less than most places sell semi-synth, you might as well get full synth...

'92 Si VTEC · Post by **jjmartin349571** » Thu Oct 03, 2013 11:59 pm

My Accord is on 78k, and is a bit rattly on the top end especially when cold. At some point I'll pull my finger out and do the valve clearences, but in the meantime would it be worth changing to 5w40 fully synth?

I'm kind of in 2 minds myself - on the one hand I'm scared of damaging the engine by changing viscosity/composition as it's a 26 year old engine, and changing the viscosity of my lower mileage 4g lude caused it to start losing oil a lot more rapidly. On the other hand, I think a lower viscosity on cold start would be kinder to the engine, and fully synth would help protect the engine better provided I don't start getting leaks everywhere... I wouldn't be so fussed on my other cars, but when the B20A2 in my Accord goes bang I will not be able to source a replacement engine

Space1999 · Post by **Space1999** » Fri Oct 04, 2013 12:57 am

It will be less likely to go bang with fully synth in it! Look at the Opie Oils website - you should be able to find 10W40 full synth easily (Gulf and Redline do them, to name but two)...

These will flow better when cold with any full synth; 5W40 it should be fine; it might use a tiny bit more oil but it should be marginal. Generally the time to use a fractionally thinner oil is winter, when it can actually give more protection, because it flows better when cold - which is when about 80% of engine wear occurs.

bennyboy · Post by **bennyboy** » Fri Oct 04, 2013 10:31 am

Space1999 wrote:If you want your engine to wear out faster, have less MPG and less BHP, and produce more sludge and potentially higher emissions, the semi-synth is fine! This is not my opinion, this is scientific, empirically measurable, fact.

Given that you can get full synth from places like Opie Oils (with whom I have no connection, by the way) for less than most places sell semi-synth, you might as well get full synth...

Sorry, what?

Yes, obviously oil tech has moved on, but I really don't think 10-40 semi (the recommended oil in the manual) has done any harm to these engines, judging by the high, problem free mileage and rude health of engines like my original A2 and plenty of others. Scaremongering IMHO.
As I said, if you're running a 'new' enigine then yes of course fully makes sense, but frankly, if it's done 90k, any 'damage' is done already

My old muzzy ran mineral oil, never skipped a beat, 40 years old, still produced near enough stock figures.

Space1999 · Post by **Space1999** » Fri Oct 04, 2013 10:41 am

Your logic is like justifying not giving up smoking because you've already smoked a lot!

Full syn is better for your engine, period. It's not just my opinion, or me scaremongering – every oil company has data sheets on their websites, showing the better performance of the fully synthetic oil they offer, over the semi or the mineral. I used to see these every day, and the data is black and white.

My point is - why buy inferior semi-syn, when you can get full syn for practically the same price if you shop around?

bennyboy · Post by **bennyboy** » Fri Oct 04, 2013 11:05 am

Space1999 wrote:Your logic is like justifying not giving up smoking because you've already smoked a lot!

No, it's not actually.

I'm not denying the benefits of fully over semi etc, what I have issue with is this:

Space1999 wrote:If you want your engine to wear out faster, have less MPG and less BHP, and produce more sludge and potentially higher emissions, the semi-synth is fine!

It just gets people scared about using an oil which has probably (or should have been) used for it up until now.
If you can get a decent fully for the price of a decent semi then knock yourself out, but FFS don't lose sleep over it if not, as long as you're using a good quality semi synth, as the manufacturer states, and changing it when you should, you're not hurting it, as mine and countless others have proven.
Don't forget, 6k is the recommended change for these engines too.

sarah_h · Post by **sarah_h** » Fri Oct 04, 2013 2:58 pm

Oh my god. What did I start here?! I only wanted to know which oil to use

89 UKDM BA4 4WS (resto job!) · Post by **wurlycorner** » Fri Oct 04, 2013 3:25 pm

jobby stirrer!

(It doesn't take much to have a good excuse for a ruck on here

)