Synthetic Oil Question

[Joey666Crack]

Growing up and through going through automotive classes, I was always told if I wanted to convert from a petroleum based oil to a full synthetic I would need to flush the system and never let the two mix because it would sludge up.

So I was going to flush out my G's oil and replace it with Royal Purple when I change my oil next, but then I did some google research and all the cool kids on Ford Forums Just say to drain and replace and some even do a 50/50 mix.

Tech opinions please. OR ANYONE WITH KNOWLEDGE <3 COBRA
Modified by Joey666Crack at 7:51 PM 4/9/2009

[SVTCOBRA]

all the cool kids on Ford Forums

which one???? I'm a member of 3 or 4 of them!

[Joey666Crack]

allfordmustangs.com

[SVTCOBRA]

allfordmustangs.com

oh...not on that one...yet!

[Joey666Crack]

So about that synthetic replacement

[SVTCOBRA]

*************************************************************************************************************************************************************8sorry, forgot you asked for tech opinions....

[Joey666Crack]

So you had it done at the dealership? I usually do all my own maintenance myself, but if it's not that expensive I guess I could have someone else do it. How much did you pay for the change?

[SVTCOBRA]

I'm not a tech...

*************deleted
Modified by SVTCOBRA at 10:37 PM 4/9/2009

[Joey666Crack]

So oil changes are considered warranty work?

This is new to me I used to be a lube tech at Toyota and they'd charge for oil changes especially synthetic.

[SVTCOBRA]

I'm very sorry for posting in this thread. I shall gtfo!!! Have a nice day!!

[Joey666Crack]

No no no I really appreciate your input, I didn't mean to limit it to techs, I edited it just for you.

[G_whizz]

I'm very sorry for posting in this thread. I shall gtfo!!! Have a nice day!!

Your in a mood eh Rich??



To my knowledge, best results would require a flush.

[joe603]

It depends. If you have a high mileage car that has had regular oil, you should flush it first. Then you run into the danger of leaks due to the properties of the regular vs. synthetic oil. (some gaskets will swell with regular oil and when you go synthetic, they shrink to normal)

Now with the G35 engine, I doubt you'll have that problem. You'll be fine to drain and replace. It is a waste to mix the regular and synthetic together.

Since you're in Fl., I recommend you use 10W-40. The VQ35 likes a higher weight oil and you'll never see temps under 0'F. I'm in Ga., and I've always used this weight with Royal Purple oils. She doesn't burn a drop

[Joey666Crack]

Thank you so much. So with like 30k I should be fine with drain and replace?

[pfarmer]

It depends. If you have a high mileage car that has had regular oil, you should flush it first. Then you run into the danger of leaks due to the properties of the regular vs. synthetic oil. (some gaskets will swell with regular oil and when you go synthetic, they shrink to normal)

Now with the G35 engine, I doubt you'll have that problem. You'll be fine to drain and replace. It is a waste to mix the regular and synthetic together.

Since you're in Fl., I recommend you use 10W-40. The VQ35 likes a higher weight oil and you'll never see temps under 0'F. I'm in Ga., and I've always used this weight with Royal Purple oils. She doesn't burn a drop

I might agree with 10-30 or whatever the manual calls for, but unless the vehicle is a high mileage one then the 10-40 over 10-30 may actually raise the operating temperature and decrease mpg.

Perry

[joe603]

Yes, but the REVUP VQ35 likes the higher weight...it may be why mine doesn't burn any oil.

I think you mean 5W-30 to 10W-40...the 5W-10W shift is the most relevant. The second number has to do with the way the oil performs when it's been warmed up.

From Carbibles:

Multigrade oils work by having a polymer added to a light base oil which prevents the oil from thinning too much as it warms up. At low temperatures, the polymers are coiled up and allow the oil to flow as it's low number (W number) indicates. As the oil heats up, the polymers unwind into long chains which prevent the oil from thinning as much as it normally would. The result is that at 100°C, the oil has thinned only as much as it's higher rating. Think of it like this: a 10W30 oil is a 10-weight oil that will not thin more than a 30-weight oil when it gets hot.

[tollboothwilley]

There is no need to flush. You can even combine them, like you read on the ford forums.

However, if you have 100K miles or close to it, I would run a High Mileage synthetic blend first...1 or 2 oil changes. Then I'd swap it to synthetic.

[pfarmer]

Yes, but the REVUP VQ35 likes the higher weight...it may be why mine doesn't burn any oil.

I think you mean 5W-30 to 10W-40...the 5W-10W shift is the most relevant. The second number has to do with the way the oil performs when it's been warmed up.

From Carbibles:

Multigrade oils work by having a polymer added to a light base oil which prevents the oil from thinning too much as it warms up. At low temperatures, the polymers are coiled up and allow the oil to flow as it's low number (W number) indicates. As the oil heats up, the polymers unwind into long chains which prevent the oil from thinning as much as it normally would. The result is that at 100°C, the oil has thinned only as much as it's higher rating. Think of it like this: a 10W30 oil is a 10-weight oil that will not thin more than a 30-weight oil when it gets hot.

The second number is the most relevant when hot. If you use an oil of a higher viscosity then necessary then several things can come into play. One is the oil will not readily flow into the areas necessary for proper lubrication. Second the rate of flow can be decreased which translates into longer than ideal retention times, therefore the rate of heat transfer will be decreased. Third it takes more effort to pump thicker oil, which contributes to less horsepower available and the engine will generate more heat in its efforts to do so. Add the third factor to the second and problems can become apparant.

So unless the engine has high mileage or other factors that may require the use of a higher viscosity oil than recommended it can actually be detrimental to do so.

As far as the difference between using 5-30 and 10-30 there have been many tests that show there is little difference especially in warmer climates so there should be no real concerns with using 5-30 in most cases. So in reality the second number probably becomes the most important number between 5-x and 10-x viscosity oils.

Perry