i own a carbed v8 3rdgen and have always put normal oil in it. today i switched over to synthetic oil, after doing so someone i know told me it could be bad for the seals in the engine? anyone know about it?

could synthetic oil be harmfull if i use it on an engine i've always used regular oil on?

 

I don't think so, I've heard on new motors use regular for about 1000 miles or so. after that I've never heard anything else bad bout it.

 

synthetic tends to remove deposits and to soften seals ,if any seals are marginal in your engine it make make then more likely to leak. to answer your question synthetic isn't bad for seal or your engine, if you have problems when you switch you'll still have them and may notice them more.

 

I've been using synthetic lubricants since 1983. I've had over a dozen vehicles in that time, and have helped several friends/family switch their vehicles over as well. I think I can say with confidence that I've come across just about every possible issue concerning synthetic use.

Having said that, I'll agree in general with what ede says above (I have seen sealing improve with continued synthetic use, for instance). If you still have any questions, feel free to ask. But, I've seen a lot of ignorance spread about here, so, feel free to PM or email me if you want to avoid having real information diluted with opinions.

 

I did a little reading on synthetics. Did you know that the definition of what a synthetic is varies by market (North America versus Europe, for example)? I think Castrol went through some litigation over this and also for varying the composition of their products without informing the consumer. Mobil 1 has also been reformulated over the years. Hard to dig some of this up as the principals aren't trumpeting it. I wonder why.

Seal problems probably won't arise if you are dealing with name-brand modern seals. Seal engineers take into account the composition of current lubricants.

 

All motor oils, atf's, brake fluids contain a swell agent for seal conditioning. Conventional motor oil with it's parrafin content will tend to deposit around seals and build up small amounts of sludge effectively making the engine tighter. It also reduces the seals exposure to swell agents as the engine ages. That's why you hear guy's say not to run it if the engine is old. While there is some truth to that you will generally need 3-5 changes before she will tighten up again. Mobil says 3 changes should remove deposits and their swell agent formula will begin to act on the seals. If you look at an engine with syn oil after 100k you would think it was brand new. It is well worth a little seeping for it's benefits.