What oil shall i use in my modded vauxhall astra MK4 1.6 8v?

Koolkuts1

Hi Guys,

Basically got a modded astra that i think is probably running around 130hp now, however the engine is slightly tappety, it still pulls like a train and theres no issues i can find mechanically wrong. At the moment its running 5w-30 but however i think this is a little thin and it probably needs something a little thicker so i was thinking maybe 5w-40 or even 0w-40?

Its due a oil change anyway and i'm not cheaping out on it this time so what do people recommend?

Really appreciate any help, and if everyone would keep on topic.

Thanks:j

AdrianC

Why do you think the 5w30 is too thin? (5w40 is the same viscosity cold, and 0w40 is thinner cold, so I guess it's the hot viscosity you're worrying about...)

What's the manufacturer recommendation? What "mods" do you have on it, and would any affect the lubricant choice?

You're already using good-brand full synth, I take it?

Geodark

What mods have you done? this may guide on oils etc. are you talking different head etc?

Koolkuts1

It has a performance exhaust header, middle box delete, air filter and a retune. Half the mods was done by the previous owner so i don't know all the ins and outs, was recommended by euro car parts to use 5w-30, don't have owners manual because previous owner lost it. Yes i'm worring about when it's hot. i put in triple QX fully synthetic.

Appreciate the help.

System

Use what the manufacturer specs. Nothing you have said would require a change of oil as it has had absolutely nothing done to the engine internals nor has it had a turbo/larger turbo added.

As it hasn't had the engine itself modded chances are the lifters are at the point of needing replacing, most certainly if it is heading for 100,000 miles. You could try the old trick of adding a litre of automatic transmission fluid to the engine oil and running it for half an hour or so before you do the oil change to remove the film of laquer that builds up on the internals of the lifter. ATF has a lot of detergent in it so its like doing an engine flush.

AdrianC

Koolkuts1 wrote: »

It has a performance exhaust header, middle box delete, air filter and a retune.

So nothing whatsoever internal? (Or particularly likely to increase power, certainly not by 30%...)

was recommended by euro car parts to use 5w-30, don't have owners manual because previous owner lost it. Yes i'm worring about when it's hot. i put in triple QX fully synthetic.

Start with a decent brand, then, not ECP own-brand cheapie.
https://www.opieoils.co.uk/c-653-5w30-engine-oil.aspx

Assuming you mean an Astra G (98-06) by "Mk4", then 5w30 is certainly what the manufacturer recommended. No reason to change that.

If it's genuinely too thin, hot, then you're most likely to see a flickering oil pressure light at hot idle. If you are seeing that, then it's more likely to be caused by internal wear than by the inlet and exhaust mods...

Koolkuts1

Okay, appreciate all the help.
It's got 73000 miles on the clock so most likely needs new tappets sometime soon, ill try the ATF trick and just stick at what i'm putting in it.

TheMoonandBack

I ran one of these and serviced it for years. Use 5w30 oil. I suspect the oil pick up pipe in the sump could be blocked, first sign usually is noisy tappets from low oil pressure.

TheTalkingDead

It wont be 130 BHP in a month of Sundays on stock parts its 84 horses stock, a tune can push it hard "safely" to around 90 horses on stock fuel injectors and rail, fuel pump and ECU after this the injectors tend to shut off or completely or fail or the pump give out or both.
This engine Hates pod/cone filters, it decreases it's power not increases it likes a good decent make panel filter instead, and the air intake box modified , and by taking out the snorkel and fitting the Vectra C intake snorkel instead (bigger more airflow), will save money on fuel too!. Look up astra G 1.6 8v Vectra C intake upgrade.


The exhaust can shift out the power the its making at the moment a header isn't going to be all that effective, unless its been port matched in the very least and at best port matched and polished.


Tappets are common issues for these 8v's and whilst they can be done in situ with a special tool, if the timing belt and tensioners need replacing (at that miles if you don't know its coming up due!) then may aswell buy a headgasket kit and torque bolts and set of new lifters. (soak lifters in engine oil 24-48 hours BEFORE you do the job, (its pretty simple following a Haynes manual if you not done it before).

Koolkuts1

TheMoonandBack wrote: »

I ran one of these and serviced it for years. Use 5w30 oil. I suspect the oil pick up pipe in the sump could be blocked, first sign usually is noisy tappets from low oil pressure.

any easy way to unblock this?

Koolkuts1

TheTalkingDead wrote: »

It wont be 130 BHP in a month of Sundays on stock parts its 84 horses stock, a tune can push it hard "safely" to around 90 horses on stock fuel injectors and rail, fuel pump and ECU after this the injectors tend to shut off or completely or fail or the pump give out or both.
This engine Hates pod/cone filters, it decreases it's power not increases it likes a good decent make panel filter instead, and the air intake box modified , and by taking out the snorkel and fitting the Vectra C intake snorkel instead (bigger more airflow), will save money on fuel too!. Look up astra G 1.6 8v Vectra C intake upgrade.


The exhaust can shift out the power the its making at the moment a header isn't going to be all that effective, unless its been port matched in the very least and at best port matched and polished.


Tappets are common issues for these 8v's and whilst they can be done in situ with a special tool, if the timing belt and tensioners need replacing (at that miles if you don't know its coming up due!) then may aswell buy a headgasket kit and torque bolts and set of new lifters. (soak lifters in engine oil 24-48 hours BEFORE you do the job, (its pretty simple following a Haynes manual if you not done it before).

i didn't do the exhaust mods, i however have unrestricted the airbox and it has a K&N panel filter in it. The number was given to me in rough from a mechanic i have no idea what its running really. I know alot of engine work was done by the previous owner inlcuding replacing the injectors, throttle body and the belts so if i was to replace tappets i would most likely get it done by using the tool. At the moment i think theyre just noisy and i doubt theyre causing too much damage to the engine so i'm not too worried.