Changed oil to 20W60, cold start shake?

[VTCJM]

Yesterday changed the oil in my VT 300K, put in penrite 20W60 and this morning when i started the car the engine started to shake really bad, the voltage readout on the display droped to around 12.5, i pushed the accelerator a bit and the engine started to pick up and idled normal after that, got me stuffed... changed plugs 3 days ago, HT leads are about 100-120K old, so maybe change them today and see how it starts tommorow, anyone used a thicker oil like 20W60? or is it too thick for my car?

[wortus]

I wouldn't change to a thicker oil unless the motor was using too much, just because it has high KM doesn't mandate a thicker oil. I had a VN with just over 300,000km and I always used Magnatec 10W40 and it didn't burn and noticable amount of oil.

Before changing the spark plug leads resistance check them and only replace them if out of spec. Also check the spark plus incase one has a crack in it.

[Cameron P]

wouldnt do you any harm to put thinner oil in to see if that was the problem??!!!

royal purple FTW!! hahaha

[VTCJM]

Went for a drive to get HT leads and the cars idle is now noticeably worse, seems to shake intermittently every couple of seconds, also did the engine mounts 6 weeks ago, very soft I can move the engine around by hand easily, so I may do the trans mount today. Spark-plugs changed last week, the connections seem all good...

see how I go after this lot...
- fuel filter
- trans mount
- change HT leads
- clean battery terminal
- clean earths, alternator connection
- buy DMM adn check coils

thought about checking leads with MM but decided to buy a new set,
if the problem persists then Im changing back to a 15w oil.

[Brett_jjj]

I use 15w 60 penrite in my VS V6 ecotec which has 150,000 on it, and have had no trouble.The oil wont be any thicker at startup than the normal 20w 50 oil, as the 50 and 60 is the oils viscosity when the oil is hot.They both have a viscosity of 20 when cold, so are the same thickness at start up.The higher number just means the oil will stay thicker at high temperatures.I use 15W 60 because it is a bit thinner at startup than the 20W stuff for quicker pressure buildup and faster flow,but then stays thicker at high temperatures to give better protection.The recommended oil for these engines is 20W 50, a 20w 40 oil is too thin and wont give as much protection when hot.Holden recommend 15W 40 when these cars are used in snowy areas in winter.

[VTCJM]

Ok 20W60 just a bit thicker at higher temp, right got ya!

All visible earths, batt connection and so on in the engine bay have been checked and cleaned, fuel filter, trans mount and leads done, still haven't checked the coils...
idles very smooth now, no bouncing around like before, and the gear changes seem a bit smoother too, doesn't clunk into drive or reverse from P.

[VTCJM]

OK quick update, had trouble other day starting car from cold start, now this morning no problem at all kicked over straight away, makes me think problem was just a temporary bad electrical connector hiccup thingamajig... no idea!

Idle is heaps better than before but still jumps a little when hot, other times it idles really nice...Got me f*****
a bit of research on here suggests that the intake manifold gasket could be knackered, looks like a prick of a job to fix up, but im guessing if it gets worse and it probably will then i might give it a go, dont lol too much, took me 2 days to do the engine mounts all i can say is mofo, hopefully intake is easier.

Next to do
- airfilter cleaned
- clean AIC, MAF, air temp sensor
- clean throttle body, remove and clean

should make a slight change to the idle I hope...

[028]

my vx started to shake at idle after replacing engine mounts