Engine oil

[Ciano91]

Hi lads, I know this is a topic well covered online but there's various opinions so said I'd ask ye.
What oil is recommended for 150kms eunos roadster?
I bought 10w40 which I taught was semi synthetic but its actually synthetic and now I have a knocking when the engine is running which wasn't there before!
So what oil should I use, 10w40 non synthetic?

Thanks in advance,
Cian

[93 Mk1]

My preference is for 10W-40 semi synthetic. I've been using this for years now and have had no issues. Some of the lighter
weight oils can show up knocks/rattles, especially with the hydraulic tappets. However, if your engine is rattly or smokey
you could go up to 15W-40 as a stop gap measure. On-schedule oil changes are more of a critical point in my opinion.

[Ciano91]

Ya the oil wasn't old in this I just said I'd change it while I was doing other bits. I'm hoping its the oil anyways, how can I know its the hydraulic tappets making the noise? I think I'll change out for 10w40 semi synthetic or 15w40 semi synthetic as I think the synthetic is just for newer stuff and is causing the tappet noise.

[93 Mk1]

Ya the oil wasn't old in this I just said I'd change it while I was doing other bits. I'm hoping its the oil anyways, how can I know its the hydraulic tappets making the noise? I think I'll change out for 10w40 semi synthetic or 15w40 semi synthetic as I think the synthetic is just for newer stuff and is causing the tappet noise.

Well, if the rattle or knock is coming from the top of the engine then it's most likely the tappets.
What oil came out in the first place ? Interesting that the tappets only got noisy with the change of oil. Was the car laid up for a while ?
I used to find that my tappets could get potentially noisy if laid up for a while but a good drive would sort it out. Another thing, are you
sure you have the correct oil level ? Low oil level or low oil pressure can also cause these symptoms.

[Ciano91]

No idea what oil came out as I havnt it that long, its being sitting up maybe a month? I didn't take it for a good drive yet I might try that tomorrow see it its any good! Oil level is all good checked it a few times and the oil pressure gauge says all is good, exact same as it was before it was laid up? And it's a mk1 so its working properly

[Ciano91]

I don't think it was coming from the bottom of the engine but if it was what could cause it?

[93 Mk1]

Take it for a good drive and get it up to operating temperature. This will take a few miles (don't assume the engine is hot
based on the water temp gauge !). The engine oil takes a good bit longer to get to temperature. Then see if the noise is
still there.
If the noise if from the bottom ? Hard to say without actually hearing it but I'd rather have worn tappets than anything in
the bottom end, let's put it that way !! To be fair though, these engines are usually pretty robust so I'd be surprised at
any bottom end problems given that the engine has 150k kms on it. (93k miles ?).

[Steve]

if its tappety its prob due a change, I've always used Castrol Magnatec 10w40 myself.

[Ciano91]

Thanks for all the replies lads went out this morning and started her, no ticking at all, brought for a long drive and put her back in the garage so she seems all good. I reckon it must be down to sitting on axle stands at the front only for a month maybe? Hadn't drove the roadster in ages forgot how great it is to drive My question now is should I take out the synthetic and go semi synthetic or leave it in? Will it do more harm then good or am I worrying about nothing?

[93 Mk1]

Personally, I'd leave it it until the next oil change, especially if it's 10W-40. Synthetic oils usually retain their properties at higher
temps but this is probably overkill on our engines. It would probably be more crucial in a turbo or supercharged situation.
Don't over think it - just enjoy the car !!

Mark.