Oil type

[vitaminZ]

Yeah i know this is a DUMB question..but I've been using synthetic blend for the past few months, and i really wanna switch to royal purple, But the guy i spoke with at my local performance store said it isn't a good idea to use full synthetic on higher millage vehicles

My car has 180K..and doesn't burn oil.

Any recommendations?

thanks.

[Z31toZ32]

not a stupid question. sythetic oil has been proven to accelerate the wear or breakdown of seals on an engine, especially when you switch back and forth. the advantages though, are that it provides better protection than dyno oil. on a turbo car, the benefits of synthetic outweigh the negatives of the potentally quicker seal breakdown. non-turbo, im not sure if the benefits are really there. and since your car is potentially approaching the end of the life at 200k (yes i know that it could go further, on average) i would personally just stick to the dyno oil.

[robomatic12]

not a stupid question. sythetic oil has been proven to accelerate the wear or breakdown of seals on an engine, especially when you switch back and forth. the advantages though, are that it provides better protection than dyno oil. on a turbo car, the benefits of synthetic outweigh the negatives of the potentally quicker seal breakdown. non-turbo, im not sure if the benefits are really there. and since your car is potentially approaching the end of the life at 200k (yes i know that it could go further, on average) i would personally just stick to the dyno oil.

Where's your proof of those so called synthetic downfalls?


It's perfectly fine to use synthetic oil on a higher mileage engine. The only thing to be aware of is that synthetic will clean away any sludge/debris inside your engine that is helping the old seals "sealing". This can cause some leaks that were always there but have been hidden by dino oil. Synthetic is much better at protecting engine components and is alot better at dealing with the high heat and resisting cooking inside the turbos when you turn off your engine. There are a lot of myths about synthetic that have been proven completely wrong. Google bobistheoilguy, you will find an entire site dedicated to oils.

[Z31toZ32]

^ alright so you got me. they dont break the seals down any faster, but on an old car will clean out deposits that had previously formed to "seal" old worn seals.

"If your engine seals are worn, the synthetic will break down the oil varnish that may be maintaining the seal. So it's not that the synthetic oil caused a leak, it just that it revealed worn seals by cleaning the varnish off of them. Many people have switched to synthetic on 100,000+ mile engines with no leaks, so it just depends on how often you changed your oil and the overall condition of your engine." http://minimopar.knizefamily.net/oil.html

if it works fine as is, im not sure id risk springing up leaks.

[robomatic12]

Correcto! I'd say just keep running what you have been running, what was your thinking behind needing to switch?

[es.biggs]

Yepp, another thing to consider is the synthetic oil has more uniform molecules that flow better than dino, which means if there are any leaks, however small they may be, synthetic will probably leak faster through them.

With that many miles, it really wouldn't be worth it. There is a saying, and it is especially true for old cars with lots of miles: If it ain't broke to don't fix it.

Preventative maintenance is the key, getting your oil changed on time is the most important part. I'd stick with the same old same old

[CrazedZ32Owner]

mobile one high milieage 5-30w thats what the guy at advance auto said, Royal purple is a no go and told me Mobile one.... and when i told him thats whats in the car he just gave me a lol.... just from running it in the car after i got the seals replaced i havent had a problem with it and i drive my Z32 pretty spiritedly

[vitaminZ]

i have 10w30 synthetic blend

[grk nickafis]

i used 10w30 valvoline full synthetic. I have 190k miles.

[Z-owned]

I went from lucas to mobil 1 to now using rp with no issues other than the rear oil pan gasket but that's leaked since I owned the car, I figure after seafoaming my car a few times I am not to worried about oil loosening up any deposits. RP seems to hold up better than the others, lucas you could feel breaking down after 500 miles or so just with touching it. I change my oil at most every 3000 miles but I feel I could go quite a bit longer on RP if I wanted. Vitaminz I tried to respond to your pm by the way but you have pm's disabled it said.

[marty1mc]

If you develop a leak because of a switch to synthetic, then you need to replace your seals anyway. I would hate the thought of my car not leaking because of sludge buildup. I have never had a problem running synthetic at any mileage on any of my cars. Not that I swap seals on a regular basis, but no leaks have developed on any of them after a switch.

[Chattzx]

Some of my engine seals leak and need to be replaced and it leaked with non synthetic just the same as with synthetic which is what I currently run. It didn't make it worse at all.